*85Pontius, J.

Plaintiff sued to recover damages to a motor vehicle under the terms of a comprehensive insurance policy, claiming that the damages arose because someone put sugar in the fuel tank of Plaintiff’s truck “during the latter part of April, 1961.” The Defendant denies that such an insurance policy was in effect on April 19, 1961, and otherwise its answer amounts to a general denial. To Defendant’s answer was attached a list of forty-two interrogatories directed to Plaintiff. Plaintiff answered the interrogatories but Defendant moved to require more complete answers by Plaintiff.

The issue presented by Defendant’s motion brings into question the proper use by a Defendant of interrogatories under Section 2309.43, Revised Code, which reads as follows:

“A party may annex to his pleading, other than a demurrer, interrogatories pertinent to the issue made in the pleadings, which interrogatories, if not demurred to, shall be plainly and fully answered under oath by the party to whom they are propounded, or if such party is a corporation, by the president, *86secretary, or other officer thereof, as the party propounding requires. ’ ’

Although the old Common Law Bill in Equity for discovery has been largely supplanted in Ohio by this code section as well as Section 2317.07, the question still remains as to whether some of the equitable principles are still in force. See Chapman v. Lee, 45 Ohio St., 356 and 365-6 of the opinion wherein the following is set forth:

“Suits for discovery were, in equity practice, auxiliary proceedings, brought not to obtain any equitable remedy, nor to establish any equitable right, but to aid in maintaining a legal right, and in prosecuting actions pending, or to be brought, in a court of law. If a party could not succeed without the aid of facts within the personal knowledge of his adversary, he might file his bill, setting forth all the facts within his knowledge, and adding interrogatories which the other party was required to answer fully under oath.”

“All the aid which a suit for recovery (discovery?) would give is now given by our code in the case at law itself. The party may attach to his pleading interrogatories which, so far as pertinent, the other party is bound to answer, and those answers may be used by either party as evidence. He may also take the deposition of the opposite party, or put him on the stand as a witness at the trial. The doctrine and rules concerning the subject-matter of discovery established by courts of equity, are believed to be still in force and to control the same matters in the new procedure, but the bill of discovery, as a separate action, is practically obsolete in this state.”

Has Ohio liberalized the discovery methods to the extent embodied in the Federal Rules of Procedure and similar statutes in some states which seem to require full disclosure of almost everything unless it is privileged?

Defendant’s answer sets up no affirmative defense. The Defendant therefore has assumed no burden of proof. The issue at first instance, at least, would seem to be narrowed to the question, may a defendant who has pleaded only a general denial áttach to his answer and have answered by the plaintiff interrogatories which only pry into the evidence by which the plaintiff may sustain his own case, as distinguished from inquiring for ultimate facts within plaintiff’s own knowledge *87which may be pertinent to the issue. In other words, does the Plaintiff have to reveal to the Defendant in advance of trial evidence which Plaintiff hopes to establish in support of his own case?

In some of the older cases in Ohio, trying to interpret this section (Section 2309.43, Bevised Code), there seems to have been established the principle that the general purpose of the discovery procedure was to aid a plaintiff in establishing his case or a defendant to establish his defense. See Chapman v. Lee, supra, Devore v. Dinsmore, 2 O. D. Rep., 600; Templeton v. Morgan, 2 O. D. Rep., 602; Graham v. Ohio Telephone and Telegraph, 15 O. D., 200. The proper use of interrogatories did not seem to extend to aiding an adversary to destroy his opponent’s case. Ward v. Mutual Trucking Company, 1 Ohio Opinions, 456. In this case Judge Carpenter pointed out that the Ohio statute, which was passed in 1857, was very similar to the English Procedural Act passed in 1854 and quoted with approval at page 457 from the opinion in Whatley v. Crowder, 119 Rep., 645, as follows:

“I think the interrogatories must be confined to matters which might be discovered by a bill of discovery in equity. I adopt the rule in the very terms used by Sir James Wigram (Wigram on Discovery, 261 [2d Ed.]): ‘The right of a plaintiff in equity to the benefit of the defendant’s oath, is limited to a discovery of such material facts as relate to the plaintiff’s case — and does not extend to a discovery of the manner in which the defendant’s ease is to be established, or to evidence which relates exclusively to his case.’ You may inquire into all that is material to your own case, though it should be in common with that of your adversary; but you may not inquire into what is exclusively his cased’ (Emphasis supplied.)

And on page 458 from Pomeroy’s Equity Jurisprudence as follows:

“The fundamental rule on this subject is, that the plaintiff’s right to a discovery does not extend to all facts which may be material to the issue, but is confined to facts which are material to his own title or cause of action; it does not enable him to pry into the defendant’s case, or find out the evidence by which that case will be supported. The plaintiff is entitled to a disclosure of the defendant’s title, and to know what his de*88fense is, but not to a statement of the evidence upon which the defendant relies to establish it.” (Emphasis supplied.)

Judge Carpenter concluded,

“Hence we must conclude the interrogatory feature of our law is intended only to aid a party in supporting his own case, and not to help him to destroy his opponent’s cause. This is in harmony with decisions in other states where this problem has been up for solution.”

Quoting from Wilson v. Webber, 68 Mass., 558, Judge Carpenter further noted at page 458:

“But it (referring to right to attach interrogatories) does not authorize the plaintiff to inquire concerning facts or documents which may be material in support of the defense; nor the defendant to seek a disclosure of those which go to make up the proofs in support of the plaintiff’s case. Each party is to be confined to those matters which are material to sustain the case which he sets up by his pleadings; he is to be allowed to obtain, by interrogating his adversary, proofs of his own case, but not those which establish the case set up against him.”

Further, in sustaining a demurrer to interrogatories, Judge Carpenter noted at page 459:

“Looking again at the character of defendant’s questions it is obvious they relate entirely to the plaintiff’s case, and their only use to the defendant is to disclose to him what plaintiff’s evidence will be in establishing his damages. The information' their answers would bring the defendant would not aid him in establishing his defenses, he has none on which he bears any burden. In other words they only ‘pry into’ the plaintiff’s case.”

Likewise, it has been held that interrogatories are not proper where the information sought is not within the personal knowledge of the other party and is not pertinent to an issue raised by the pleading of the inquirer. Russell v. Lake Shore and Michigan Southern Railroad, 6 O. N. P. N. S., 353. It has been held that interrogatories are not proper where the answer calls for mere opinion of the party, Smith v. Corey Rubber, 32 Ohio Opinions, 308, nor where the information sought is not within the personal knowledge of the party interrogated. Russell v. Lake Shore and Michigan Southern, supra.

In more recent cases it has been held that this statute and *89likewise its counterpart must be liberally construed and that interrogatories are proper if they are designed to seek information pertinent to the action as distinguished from being merely pertinent to an issue raised by the pleading of the inquirer. See Sloan v. S. S. Kresge Company, 48 Ohio Opinions, 407, 55 Ohio Law Abs., 420; Powers v. Ruelbach, 49 Ohio Opinions, 54, 66 Ohio Law Abs., 30; Dieckbrader v. New York Central, 51 Ohio Opinions, 239, 64 Ohio Law Abs., 586; Feinstein v. Cleveland, 67 Ohio Law Abs., 518, “Interrogatories may seek information relevant to any issue of the action and to all sides of the case.” (Emphasis supplied.)

Parenthetically, it also may be observed that this same philosophy is to prevail when the information is sought by way of deposition and the inspection and production of documents is sought under Section 2317.32, Revised Code. See In re Keough, 151 Ohio St., 307. Many states have liberalized their statutory procedure, pointing toward, if not actually adopting, the very extreme liberal rules of discovery as provided by rules 26 through 43 of the Federal Rules of Procedure. 3 Jones on Evidence, 5th ed., Chap. XV sheds some light on this controversial subject even under the more modern cases and statutes.

In Hickman v. Taylor, 329 U. S., 495, 34 Ohio Opinions, 394, in a very hotly contested case the Court was dealing with the matter of discovery under the Federal Rules. Even under these very liberal rules, the United States Supreme Court refused the claim of the plaintiff to a discovery of what prospective witnesses had told defense counsel and refused plaintiff copies of statements taken from them.

Certainly the Ohio statute of 1857, regardless of what interpretation may be put upon it, does not go as far nor is it as liberal as the Federal Rules of Practice, at least because two additional factors are present: — one, that the interrogatory must be pertinent to the issue made in the pleadings, and two, if admissible in evidence, the answer may be read by either party. (Section 2309.45, Revised Code.)

This Court is inclined to the more liberal and later construction of the Ohio statutes as disclosed by Sloan v. S. S. Kresge, rather than the older rule indicated in such cases as Devore v. Dinsmore, supra, and even Ward v. Mutual Trucking Company; and this Court holds to the view that interrogatories, whether filed with a pleading under favor of Section 2309.43, *90Revised Code, or separately under Section 2317.07, Revised Code, are proper when:

1. Relevant to an issue in the action as distinguished from merely being relevant to an issue in the pleading of the inquirer,

2. They do not seek privileged information,

3. The information sought would also be admissible as evidence in the action.

The rule is limited, however, by the further rule that interrogatories may not seek discovery of the manner whereby the opponent’s case is to be established nor evidence which relates exclusively to his case, nor to what his witnesses will testify.

In this Court’s opinion, there is a marked distinction between records kept by a party in the regular course of his business operations and those amassed by him only after an incident has arisen out of which his lawsuit or defense arises. The former may be ordered produced, if pertinent to an issue in the action; the latter may not. See ex parte Schoepf, 74 Ohio St., 1; In re Hyde, 149 Ohio St., 407; In re Keough, supra; In re Shoup, 154 Ohio St., 21; In re Tichy, 161 Ohio St., 104.

With these rules in mind further inquiry directed toward the interrogatories of Defendant and answers by Plaintiff must be made.

The issues in the case as presented by the petition and the answer as distinguished from issues in only one pleading or the other would seem to be:

1. Did the Plaintiff hold a comprehensive insurance policy issued by the Defendant, which policy was in force in the latter part of April, 1961?

2. Did the policy cover a 1955 White tractor (owned by Plaintiff) ?

3. Was sugar placed in the mechanism of this tractor?

4. Was the tractor damaged thereby and if so, to what extent?

Defendant’s interrogatory number 2 calls upon Plaintiff to state whether she was the sole proprietor of a trucking business or whether same was a partnership or corporation at the time of Plaintiff’s claim. This interrogatory has a direct bearing on the question of truck ownership and policy coverage. The Plaintiff’s answer to the interrogatory is equivocal. The *91Plaintiff therefore will be directed to answer the interrogatory fully and completely, stating whether she owned the business as a sole proprietor or as a member of a partnership and if so, the other members thereof, or whether the business was incorporated.

Interrogatory number 6 calls for Plaintiff to state where the truck was at the time the sugar allegedly got into the mechanism of the truck. The answer given is “Don’t personally know.” Bearing in mind that previous interrogatories and answers thereto reveal the fact that the truck in question was under the care and custody of someone else other than Plaintiff, it would seem as though Plaintiff’s answer to this interrogatory is full and complete. The motion with respect to interrogatory and answer number 6 is therefore overruled.

Interrogatories numbers 10, 12, and 15 through 33 all deal with matters arising at the time of or after Plaintiff’s alleged claim arose. None deal with information or records maintained in the normal operation of Plaintiff’s business. On the contrary, they call for information as to the manner in which the Plaintiff may attempt to establish her cause of action and do not countenance information presumably within Plaintiff’s own personal knowledge. They call for information which Plaintiff may or may not be able to produce through testimony of witnesses upon trial. In other words, they call for hearsay or mere opinion evidence if Plaintiff’s answer of “Don’t personally know” is true. Certainly upon trial if Plaintiff were so inquired of and should so answer the same or similar interrogatories, she could not then be called upon to give her opinion or an answer which was obviously mere hearsay.

The same objection is true with interrogatories 36 and 37 and the answers given thereto; and likewise interrogatories 39 through 42 and Plaintiff’s answers thereto. An additional objection to interrogatory number 42 exists, namely, assuming that a record of a test was made, it calls for the furnishing of information solely in support of Plaintiff’s cause of action and obviously arises after the claim arose and in connection with Plaintiff’s preparation for presentation of her claim and her lawsuit. This last mentioned objection is likewise true with many of the other interrogatories heretofore above covered.

Defendant’s motion therefore will be overruled in all re*92spects except with reference to tbe answer given by Plaintiff to interrogatory number 2, and Plaintiff is directed to file a complete answer as above indicated.

Counsel for Plaintiff will prepare and submit an appropriate Journal Entry.

Mr. Justice Murphy

delivered the opinion of the Court.

This case presents an important problem under the Federal Rules of Civil Procedure as to the extent to which a party may inquire into oral and written statements of witnesses, or other information, secured by an adverse party’s counsel in the course of preparation for possible litigation after a claim has arisen. Examination into a person’s files and records, including those resulting from the professional activities of an attorney, must be judged with care. It is not without reason that various safeguards have been established to preclude unwarranted excursions into the privacy of a man’s work. At the same time, public policy supports reasonable and necessary inquiries. Properly to balance these competing interests is a delicate and difficult task.

*498On February 7, 1943, the tug “J. M. Taylor” sank while engaged in helping to tow a car float of the Baltimore & Ohio Railroad across the Delaware River at Philadelphia. The accident was apparently unusual in nature, the cause of it still being unknown. Five of the nine crew members were drowned. Three days later the tug owners and the underwriters employed a law firm, of which respondent Fortenbaugh is a member, to defend them against potential suits by representatives of the deceased crew members and to sue the railroad for damages to the tug.

A public hearing was held on March 4, 1943, before the United States Steamboat Inspectors, at which the four survivors were examined. This testimony was recorded and made available to all interested parties. Shortly thereafter, Fortenbaugh privately interviewed the survivors and took statements from them with an eye toward the anticipated litigation; the survivors signed these statements on March 29. Fortenbaugh also interviewed other persons believed to have some information relating to the accident and in some cases he made memoranda of what they told him. At the time when Fortenbaugh secured the statements of the survivors, representatives of two of the deceased crew members had been in communication with him. Ultimately claims were presented by representatives of all five of the deceased; four of the claims, however, were settled without litigation: The fifth claimant, petitioner herein, brought suit in a federal court under the Jones Act on November 26,1943, naming as defendants the two tug owners, individually and as partners, and the railroad.

One year later, petitioner filed 39 interrogatories directed to the tug owners. The 38th interrogatory read: “State whether any statements of the members of the crews of the Tugs ‘J. M. Taylor’ and ‘Philadelphia’ or of any other vessel were taken in connection with the towing of the car float and the sinking of the Tug ‘John M. Tay*499lor.’ Attach hereto exact copies of all such statements if in writing, and if oral, set forth in detail the exact provisions of any such oral statements or reports.”

Supplemental interrogatories asked whether any oral or written statements, records, reports or other memoranda had been made concerning any matter relative to the towing operation, the sinking of the tug, the salvaging and repair of the tug, and the death of the deceased. If the answer was in the affirmative, the tug owners were then requested to set forth the nature of all such records, reports, statements or other memoranda.

The tug owners, through Fortenbaugh, answered all of the interrogatories except No. 38 and the supplemental ones just described. While admitting that statements of the survivors had been taken, they declined to summarize or set forth the contents. They did so on the ground that such requests called “for privileged matter obtained in preparation for litigation” and constituted “an attempt to obtain indirectly counsel’s private files.” It was claimed that answering these requests “would involve practically turning over not only the complete files, but also the telephone records and, almost, the thoughts of counsel.”

In connection with the hearing on these objections, Fortenbaugh made a written statement and gave an informal oral deposition explaining the circumstances under which he had taken the statements. But he was not expressly asked in the deposition to produce the statements. The District Court for the Eastern District of Pennsylvania, sitting en banc, held that the requested matters were not privileged. 4 F. R. D. 479. The court then decreed that the tug owners and Fortenbaugh, as counsel and agent for the tug owners, forthwith “answer Plaintiff’s 38th interrogatory and supplementary interrogatories; produce all written statements of witnesses obtained by Mr. Fortenbaugh, as counsel and agent for Defendants; *500state in substance any fact concerning this case which Defendants learned through oral statements made by witnesses to Mr. Fortenbaugh whether or not included in his private memoranda and produce Mr. Fortenbaugh's mem-oranda containing statements of fact by witnesses or to submit these memoranda to the Court for determination of those portions which should be revealed to Plaintiff.” Upon their refusal, the court adjudged them in contempt and ordered them imprisoned until they complied.

The Third Circuit Court of Appeals, also sitting en banc, reversed the judgment of the District Court. 153 F. 2d 212. It held that the information here sought was part of the “work product of the lawyer” and hence privileged from discovery under the Federal Rules of Civil Procedure. The importance of the problem, which has engendered a great divergence of views among district courts,1 led us to grant certiorari. 328 U. S. 876.

The pre-trial deposition-discovery mechanism established by Rules 26 to 37 is one of the most significant innovations of the Federal Rules of Civil Procedure. Under the prior federal practice, the pre-trial functions of notice-giving, issue-formulation and fact-revelation were performed primarily and inadequately by the pleadings.2 Inquiry into the issues and the facts before trial was *501narrowly confined and was often cumbersome in method.3 The new rules, however, restrict the pleadings to the task of general notice-giving and invest the deposition-discovery process with a vital role in the preparation for trial. The various instruments of discovery now serve (1) as a device, along with the pre-trial hearing under Rule 16, to narrow and clarify the basic issues between the parties, and (2) as a device for ascertaining the facts, or information as to the existence or whereabouts of facts, relative to those issues. Thus civil trials in the federal courts no longer need be carried on in the dark. The way is now clear, consistent with recognized privileges, for the parties to obtain the fullest possible knowledge of the issues and facts before trial.4

There is an initial question as to which of the deposition-discovery rules is involved in this case. Petitioner, in filing his interrogatories, thought that he was proceeding under Rule 33. That rule provides that a party may serve upon any adverse party written interrogatories to be answered by the party served.5 The District Court pro*502ceeded on the same assumption in its opinion, although its order to produce and its contempt order stated that both Rules 33 and 34 were involved. Rule 34 establishes a procedure whereby, upon motion of any party showing good cause therefor and upon notice to all other parties, the court may order any party to produce and permit the inspection and copying or photographing of any designated documents, etc., not privileged, which constitute or contain evidence material to any matter involved in the action and which are in his possession, custody or control.6

The Circuit Court of Appeals, however, felt that Rule 26 was the crucial one. Petitioner, it said, was proceeding by interrogatories and, in connection with those interrogatories, wanted copies of memoranda and statements secured from witnesses. While the court believed that Rule 33 was involved, at least as to the defending tug owners, it stated that this rule could not be used as the basis for condemning Fortenbaugh’s failure to disclose or produce *503the memoranda and statements, since the rule applies only to interrogatories addressed to adverse parties, not to their agents or counsel. And Rule 34 was said to be inapplicable since petitioner was not trying to see an original document and to copy or photograph it, within the scope of that rule. The court then concluded that Rule 26 must be the one really involved. That provides that the testimony of any person, whether a party or not, may be taken by any party by deposition upon oral examination or written interrogatories for the purpose of discovery or for use as evidence; and that the deponent may be examined regarding any matter, not privileged, which is relevant to the subject matter involved in the pending action, whether relating to the claim or defense of the examining party or of any other party, including the existence, description, nature, custody, condition and location of any books, documents or other tangible things.7

*504The matter is not without difficulty in light of the events that transpired below. We believe, however, that petitioner was proceeding primarily under Rule 33. He addressed simple interrogatories solely to the individual tug owners, the adverse parties, as contemplated by that rule. He did not, and could not under Rule 33, address such interrogatories to their counsel, Fortenbaugh. Nor did he direct these interrogatories either to the tug owners or to Fortenbaugh by way of deposition; Rule 26 thus could not come into operation. And it does not appear from the record that petitioner filed a motion under Rule 34 for a court order directing the production of the documents in question. Indeed, such an order could not have been entered as to Fortenbaugh since Rule 34, like Rule 33, is limited to parties to the proceeding, thereby excluding their counsel or agents.

Thus to the extent that petitioner was seeking the production of the memoranda and statements gathered by Fortenbaugh in the course of his activities as counsel, petitioner misconceived his remedy. Rule 33 did not permit him to obtain such memoranda and statements as adjuncts to the interrogatories addressed to the individual tug owners. A party clearly cannot refuse to answer interrogatories on the ground that the information sought is solely within the knowledge of his attorney. But that is not this case. Here production was sought of documents prepared by a party's attorney after the claim has arisen. Rule 33 does not make provision for such production, even when sought in connection with permissible interrogatories. Moreover, since petitioner was also foreclosed from securing them through an order under Rule 34, his only recourse was to take Fortenbaugh’s deposition under Rule 26 and to attempt to force Fortenbaugh to produce the materials by use of a subpoena duces tecum, in accordance with Rule 45. Holtzoff, “Instruments of Discovery under the Federal Rules of Civil Procedure,” 41 *505Mich. L. Rev. 205, 220. But despite petitioner’s faulty-choice of action, the District Court entered an order, apparently under Rule 34, commanding the tug owners and Fortenbaugh, as their agent and counsel, to produce the materials in question. Their refusal led to the anomalous result of holding the tug owners in contempt for failure to produce that which was in the possession of their counsel and of holding Fortenbaugh in contempt for failure to produce that which he could not be compelled to produce under either Rule 33 or Rule 34.

But, under the circumstances, we deem it unnecessary and unwise to rest our decision upon this procedural irregularity, an irregularity which is not strongly urged upon us and which was disregarded in the two courts below. It matters little at this late stage whether Fortenbaugh fails to answer interrogatories filed under Rule 26 or under Rule 33 or whether he refuses to produce the memoranda and statements pursuant to a subpoena under Rule 45 or a court order under Rule 34. The deposition-discovery rules create integrated procedural devices. And the basic question at stake is whether any of those devices may be used to inquire into materials collected by an adverse party’s counsel in the course of preparation for possible litigation. The fact that the petitioner may have used the wrong method does not destroy the main thrust of his attempt. Nor does it relieve us of the responsibility of dealing with the problem raised by that attempt. It would be inconsistent with the liberal atmosphere surrounding these rules to insist that petitioner now go through the empty formality of pursuing the right procedural device only to reestablish precisely the same basic problem now confronting us. We do not mean to say, however, that there may not be situations in which the failure to proceed in accordance with a specific rule would be important or decisive. But in the present circumstances, for the purposes of this decision, the procedural *506irregularity is not material. Having noted the proper procedure, we may accordingly turn our attention to the substance of the underlying problem.

In urging that he has a right to inquire into the materials secured and prepared by Fortenbaugh, petitioner emphasizes that the deposition-discovery portions of the Federal Rules of Civil Procedure are designed to enable the parties to discover the true facts and to compel their disclosure wherever they may be found. It is said that inquiry may be made under these rules, epitomized by Rule 26, as to any relevant matter which is not privileged ; and since the discovery provisions are to be applied as broadly and liberally as possible, the privilege limitation must be restricted to its narrowest bounds. On the premise that the attorney-client privilege is the one involved in this case, petitioner argues that it must be strictly confined to confidential communications made by a client to his attorney. And since the materials here in issue were secured by Fortenbaugh from third persons rather than from his clients, the tug owners, the conclusion is reached that these materials are proper subjects for discovery under Rule 26.

As additional support for this result, petitioner claims that to prohibit discovery under these circumstances would give a corporate defendant a tremendous advantage in a suit by an individual plaintiff. Thus in a suit by an injured employee against a railroad or in a suit by an insured person against an insurance company the corporate defendant could pull a dark veil of secrecy over all the pertinent facts it can collect after the claim arises merely on the assertion that such facts were gathered by its large staff of attorneys and claim agents. At the same time, the individual plaintiff, who often has direct knowledge of the matter in issue and has’no counsel until some time after his claim arises could be compelled to disclose all the intimate details of his case. By endowing with *507immunity from disclosure all that á lawyer discovers in the course of his duties, it is said, the rights of individual litigants in such cases are drained of vitality and the lawsuit becomes more of a battle of deception than a search for truth.

But framing the problem in terms of assisting individual plaintiffs in their suits against corporate defendants is unsatisfactory. Discovery concededly may work to the disadvantage as well as to the advantage of individual plaintiffs. Discovery, in other words, is not a one-way proposition. It is available in all types of cases at the behest of any party, individual or corporate, plaintiff or defendant. The problem thus far transcends the situation confronting- this petitioner. And we must view that problem in light of the limitless situations where the particular kind of discovery sought by petitioner might be used.

We agree, of course, that the deposition-discovery rules are to be accorded a broad and liberal treatment. No longer can the time-honored cry of “fishing expedition” serve to preclude a party from inquiring into the facts underlying his opponent’s case.8 Mutual knowledge of all the relevant facts gathered by both parties is essential to proper litigation. To that end, either party may compel the other to disgorge whatever facts he has in his possession. The deposition-discovery procedure simply advances the stage at which the disclosure can be compelled from the time of trial to the period preceding it, thus reducing the possibility of surprise. But discovery, like all matters of procedure, has ultimate and necessary boundaries. As indicated by Rules 30 (b) and (d) and 31 (d), limitations inevitably arise when it can be shown *508that the examination is being conducted in bad faith or in such a manner as to annoy, embarrass or oppress the person subject to the inquiry. And as Rule 26 (b) provides, further limitations come into existence when the inquiry touches upon the irrelevant or encroaches upon the recognized domains of privilege.

We also agree that the memoranda, statements and mental impressions in issue in this case fall outside the scope of the attorney-client privilege and hence are not protected from discovery on that basis. It is unnecessary here to delineate the content and scope of that privilege as recognized in the federal courts. For present purposes, it suffices to note that the protective cloak of this privilege does not extend to information which an attorney secures from a witness while acting for his client in anticipation of litigation. Nor does this privilege concern the memo-randa, briefs, communications and other writings prepared by counsel for his own use in prosecuting his client’s case; and it is equally unrelated to writings which reflect an attorney’s mental impressions, conclusions, opinions or legal theories.

But the impropriety of invoking that privilege does not provide an answer to the problem before us. Petitioner has made more than an ordinary request for relevant, non-privileged facts in the possession of his adversaries or their counsel. He has sought discovery as of right of oral and written statements of witnesses whose identity is well known and whose availability to petitioner appears unimpaired. He has sought production of these matters after making the most searching inquiries of his opponents as to the circumstances surrounding the fatal accident, which inquiries were sworn to have been answered to the best of their information and belief. Interrogatories were directed toward all the events prior to, during and subsequent to the sinking of the tug. Full and honest answers to such broad inquiries would necessarily have included all *509pertinent information gleaned by Fortenbaugh through his interviews with the witnesses. Petitioner makes no suggestion, and we cannot assume, that the tug owners or Fortenbaugh were incomplete or dishonest in the framing of their answers. In addition, petitioner was free to examine the public testimony of the witnesses taken before the United States Steamboat Inspectors. We are thus dealing with an attempt to secure the production of written statements and mental impressions contained in the files and the mind of the attorney Fortenbaugh without any showing of necessity or any indication or claim that denial of such production would unduly prejudice the preparation of petitioner’s case or cause him any hardship or injustice. For aught that appears, the essence of what petitioner seeks either has been revealed to him already through the interrogatories or is readily available to him direct from the witnesses for the asking.

The District Court, after hearing objections to petitioner’s request, commanded Fortenbaugh to produce all written statements of witnesses and to state in substance any facts learned through oral statements of witnesses to him. Fortenbaugh was to submit any memoranda he had made of the oral statements so that the court might determine what portions should be revealed to petitioner. All of this was ordered without any showing by petitioner, or any requirement that he make a proper showing, of the necessity for the production of any of this material or any demonstration that denial of production would cause hardship or injustice. The court simply ordered production on the theory that the facts sought were material and were not privileged as constituting attorney-client communications.

In our opinion, neither Rule 26 nor any other rule dealing with discovery contemplates production under such circumstances. That is not because the subject matter is privileged or irrelevant, as those concepts are used in these *510rules.9 Here is simply an attempt, without purported necessity or justification, to secure written statements, private memoranda and personal recollections prepared or formed by an adverse party’s counsel in the course of his legal duties. As such, it falls outside the arena of discovery and contravenes the public policy underlying the orderly prosecution and defense of legal claims. Not even the most liberal of discovery theories can justify unwarranted inquiries into the files and the mental impressions of an attorney.

Historically, a lawyer is an officer of the court and is bound to work for the advancement of justice while faithfully protecting the rightful interests of his clients. In performing his various duties, however, it is essential that a lawyer work with a certain degree of privacy, free from unnecessary intrusion by opposing parties and their coun*511sel. Proper preparation of a client’s case demands that he assemble information, sift what he considers to be the relevant from the irrelevant facts, prepare his legal theories and plan his strategy without undue and needless interference. That is the historical and the necessary way in which lawyers act within the framework of our system of jurisprudence to promote justice and to protect their clients’ interests. This work is reflected, of course, in interviews, statements, memoranda, correspondence, briefs, mental impressions, personal beliefs, and countless other tangible and intangible ways — aptly though roughly termed by the Circuit Court of Appeals in this case as the “work product of the lawyer.” Were such materials open to opposing counsel on mere demand, much of what is now put down in writing would remain unwritten. An attorney’s thoughts, heretofore inviolate, would not be his own. Inefficiency, unfairness and sharp practices would inevitably develop in the giving of legal advice and in the preparation of cases for trial. The effect on the legal profession would be demoralizing. And the interests of the clients and the cause of justice would be poorly served.

We do not mean to say that all written materials obtained or prepared by an adversary’s counsel with an eye toward litigation are necessarily free from discovery in all cases. Where relevant and non-privileged facts remain hidden in an attorney’s file and where production of those facts is essential to the preparation of one’s case, discovery may properly be had. Such written statements and documents might, under certain circumstances, be admissible in evidence or give clues as to the existence or location of relevant facts. Or they might be useful for purposes of impeachment or corroboration. And production might be justified where the witnesses are no longer available or can be reached only with difficulty. Were production of written statements and documents to be precluded under *512such circumstances, the liberal ideals of the deposition-discovery portions of the Federal Rules of Civil Procedure would be stripped of much of their meaning. But the general policy against invading the privacy of an attorney’s course of preparation is so well recognized and so essential to an orderly working of our system of legal procedure that a burden rests on the one who would invade that privacy to establish adequate reasons to justify production through a subpoena or court order. That burden, we believe, is necessarily implicit in the rules as now constituted.10

Rule 30 (b), as presently written, gives the trial judge the requisite discretion to make a judgment as to whether discovery should be allowed as to written statements secured from witnesses. But in the instant case there was no room for that discretion to operate in favor of the petitioner. No attempt was made to establish any reason why Fortenbaugh should be forced to produce the written statements. There was only a naked, general demand for these materials as of right and a finding by the District Court that no recognizable privilege was involved. That was insufficient to justify discovery under these circumstances and the court should have sustained the refusal of the tug owners and Fortenbaugh to produce.

But as to oral statements made by witnesses to Forten-baugh, whether presently in the form of his mental impressions or memoranda, we do not believe that any showing of necessity can be made under the circumstances of this case so as to justify production. Under ordinary conditions, forcing an attorney to repeat or write out all that witnesses have told him and to deliver the account *513to his adversary gives rise to grave dangers of inaccuracy and untrustworthiness. No legitimate purpose is served by such production. The practice forces the attorney to testify as to what he remembers or what he saw fit to write down regarding witnesses’ remarks. Such testimony could not qualify as evidence; and to use it for impeachment or corroborative purposes would make the attorney much less an officer of the court and much more an ordinary witness. The standards of the profession would thereby suffer.

Denial of production of this nature does not mean that any material, non-privileged facts can be hidden from the petitioner in this case. He need not be unduly hindered in the preparation of his case, in the discovery of facts or in his anticipation of his opponents’ position. Searching interrogatories directed to Fortenbaugh and the tug owners, production of written documents and statements upon a proper showing and direct interviews with the witnesses themselves all serve to reveal the facts in Fortenbaugh’s possession to the fullest possible extent consistent with public policy. Petitioner’s counsel frankly admits that he wants the oral statements only to help prepare himself to examine witnesses and to make sure that he has overlooked nothing. That is insufficient under the circumstances to permit him an exception to the policy underlying the privacy of Fortenbaugh’s professional activities. If there should be a rare situation justifying production of these matters, petitioner’s case is not of that type.

We fully appreciate the wide-spread controversy among the members of the legal profession over the problem raised by this case.11 It is a problem that rests on what *514has been one of the most hazy frontiers of the discovery process. But until some rule or statute definitely prescribes otherwise, we are not justified in permitting discovery in a situation of this nature as a matter of unqualified right. When Rule 26 and the other discovery rules were adopted, this Court and the members of the bar in general certainly did not believe or contemplate that all the files and mental processes of lawyers were thereby opened to the free scrutiny of their adversaries. And we refuse to interpret the rules at this time so as to reach so harsh and unwarranted a result.

We therefore affirm the judgment of the Circuit Court of Appeals.

Affirmed.

Mr. Justice Jackson,

concurring.

The narrow question in this case concerns only one of thirty-nine interrogatories which defendants and their counsel refused to answer. As there was persistence in refusal after the court ordered them to answer it, counsel and clients were committed to jail by the district court until they should purge themselves of contempt.

The interrogatory asked whether statements were taken from the crews of the tugs involved in the accident, or of any other vessel, and demanded “Attach hereto exact copies of all such statements if in writing, and if oral, set forth in detail the exact provisions of any such oral statements or reports.” The question is simply whether such a demand is authorized by the rules relating to various aspects of “discovery.”

The primary effect of the practice advocated here would be on the legal profession itself. But it too often is over*515looked that the lawyer and the law office are indispensable parts of our administration of justice. Law-abiding people can go nowhere else to learn the ever changing and constantly multiplying rules by which they must behave and to obtain redress for their wrongs. The welfare and tone of the legal profession is therefore of prime consequence to society, which would feel the consequences of such a practice as petitioner urges secondarily but certainly.

“Discovery” is one of the working tools of the legal profession. It traces back to the equity bill of discovery in English Chancery practice and seems to have had a forerunner in Continental practice. See Ragland, Discovery Before Trial (1932) 13-16. Since 1848 when the draftsmen of New York’s Code of Procedure recognized the importance of a better system of discovery, the impetus to extend and expand discovery, as well as the opposition to it, has come from within the Bar itself. It happens in this case that it is the plaintiff’s attorney who demands such unprecedented latitude of discovery and, strangely enough, amicus briefs in his support have been filed by several labor unions representing plaintiffs as a class. It is the history of the movement for broader discovery, however, that in actual experience the chief opposition to its extension has come from lawyers who specialize in representing plaintiffs, because defendants have made liberal use of it to force plaintiffs to disclose their cases in advance. See Report of the Commission on the Administration of Justice in New York State (1934) 330-31; Rag-land, Discovery Before Trial (1932) 35-36. Discovery is a two-edged sword and we cannot decide this problem on any doctrine of extending help to one class of litigants.

It seems clear and long has been recognized that discovery should provide a party access to anything that is evidence in his case. Cf. Report of Commission on the Administration of Justice in New York State (1934) 41-42. *516It seems equally clear that discovery should not nullify the privilege of confidential communication between attorney and client. But those principles give us no real assistance here because what is being sought is neither evidence nor is it a privileged communication between attorney and client.

To consider first the most extreme aspect of the requirement in litigation here, we find it calls upon counsel, if he has had any conversations with any of the crews of the vessels in question or of any other, to “set forth in detail the exact provision of any such oral statements or reports.” Thus the demand is not for the production of a transcript in existence but calls for the creation of a written statement not in being. But the statement by counsel of what a witness told him is not evidence when written. Plaintiff could not introduce it to prove his case. What, then, is the purpose sought to be served by demanding this of adverse counsel?

Counsel for the petitioner candidly said on argument that he wanted this information to help prepare himself to examine witnesses, to make sure he overlooked nothing. He bases his claim to it in his brief on the view that the Rules were to do away with the old situation where a law suit developed into “a battle of wits between counsel.” But a common law trial is and always should be an adversary proceeding. Discovery was hardly intended to enable a learned profession to perform its functions either without wits or on wits borrowed from the adversary.

The real purpose and the probable effect of the practice ordered by the district court would be to put trials on a level even lower than a “battle of wits.” I can conceive of no practice more demoralizing to the Bar than to require a lawyer to write out and deliver to his adversary an account of what witnesses have told him. Even if his recollection were perfect, the statement would be his lan*517guage, permeated with his inferences. Every one who has tried it knows that it is almost impossible so fairly to record the expressions and emphasis of a witness that when he testifies in the environment of the court and under the influence of the leading question there will not be departures in some respects. Whenever the testimony of the witness would differ from the “exact” statement the lawyer had delivered, the lawyer’s statement would be whipped out to impeach the witness. Counsel producing his adversary’s “inexact” statement could lose nothing by saying, “Here is a contradiction, gentlemen of the jury. I do not know whether it is my adversary or his witness who is not telling the truth, but one is not.” Of course, if this practice were adopted, that scene would be repeated over and over again. The lawyer who delivers such statements often would find himself branded a deceiver afraid to take the stand to support his own version of the witness’s conversation with him, or else he will have to go on the stand to defend his own credibility — perhaps against that of his chief witness, or possibly even his client.

Every lawyer dislikes to take the witness stand and will do so only for grave reasons. This is partly because it is not his role; he is almost invariably a poor witness. But he steps out of professional character to do it. He regrets it; the profession discourages it. But the practice advocated here is one which would force him to be a witness, not as to what he has seen or done but as to other witnesses’ stories, and not because he wants to do so but in self-defense.

And what is the lawyer to do who has interviewed one whom he believes to be a biased, lying or hostile witness to get his unfavorable statements and know what to meet? He must record and deliver such statements even though he would not vouch for the credibility of the witness by calling him. Perhaps the other side would not want to *518call him either, but the attorney is open to the charge of suppressing evidence at the trial if he fails to call such a hostile witness even though he never regarded him as reliable or truthful.

Having been supplied the names of the witnesses, petitioner’s lawyer gives no reason why he cannot interview them himself. If an employee-witness refuses to tell his story, he, too, may be examined under the Rules. He may be compelled on discovery, as fully as on the trial, to disclose his version of the facts. But that is his own disclosure — it can be used to impeach him if he contradicts it and such a deposition is not useful to promote an unseemly disagreement between the witness and the counsel in the case.

It is true that the literal language of the Rules would admit of an interpretation that would sustain the district court’s order. So the literal language of the Act of Congress which makes “any writing or record . . . made as a memorandum or record of any . . . occurrence, or event” admissible as evidence, would have allowed the railroad company to put its engineer’s accident statements in evidence. Cf. Palmer v. Hoffman, 318 U. S. 109, 111. But all such procedural measures have a background of custom and practice which was assumed by those who wrote and should be by those who apply them. We reviewed the background of the Act and the consequences on the trial of negligence cases of allowing railroads and others to put in their statements and thus to shield the crew from cross-examination. We said, “Such a major change which opens wide the door to avoidance of cross-examination should not be left to implication.” 318 U. S. at 114. We pointed out that there, as here, the “several hundred years of history behind the Act . . . indicate the nature of the reforms which it was designed to effect.” *519318 U. S. at 115. We refused to apply it beyond that point. We should follow the same course of reasoning here. Certainly nothing in the tradition or practice of discovery up to the time of these Rules would have suggested that they would authorize such a practice as here proposed.

The question remains as to signed statements or those written by witnesses. Such statements are not evidence for the defendant. Palmer v. Hoffman, 318 U. S. 109. Nor should I think they ordinarily could be evidence for the plaintiff. But such a statement might be useful for impeachment of the witness who signed it, if he is called and if he departs from the statement. There might be circumstances, too, where impossibility or difficulty of access to the witness or his refusal to respond to requests for information or other facts would show that the interests of justice require that such statements be made available. Production of such statements are governed by Rule 34 and on “showing good cause therefor” the court may order their inspection, copying or photographing. No such application has here been made; the demand is made on the basis of right, not on showing of cause.

I agree to the affirmance of the judgment of the Circuit Court of Appeals which reversed the district court.

Mr. Justice Frankfurter joins in this opinion.