In an action, inter alia, to set aside a prenuptial agreement, the plaintiff appeals, as limited by her brief, from so much of an order of the Supreme Court, Nassau County (Falanga, J.), dated August 1, 2008, as granted those branches of the defendant’s motion which were for summary judgment dismissing the second, third, and sixth causes of action, and stated portions of the eighth and tenth causes of action.

Ordered that the order is affirmed insofar as appealed from, with costs.

An agreement between spouses or prospective spouses which is fair on its face will be enforced according to its terms unless there is proof of fraud, duress, overreaching, or unconscionability (see Christian v Christian, 42 NY2d 63, 72-73 [1977]; Label v Label, 70 AD3d 898 [2010]). “An unconscionable bargain is one which no person in his or her senses and not under delusion would make on the one hand, and no honest and fair person would accept on the other, the inequality being so strong and *869manifest as to shock the conscience and confound the judgment of any person of common sense” (Morad v Morad, 27 AD3d 626, 627 [2006]; see Christian v Christian, 42 NY2d at 71). An agreement, however, will not be overturned “ ‘merely because, in retrospect, some of its provisions were improvident or one-sided’ ” (Label v Label, 70 AD3d at 899, quoting O’Lear v O’Lear, 235 AD2d 466 [1997]), and simply alleging an unequal division of assets is not sufficient to establish unconscionability (see Cosh v Cosh, 45 AD3d 798, 799 [2007]).

Here, the record demonstrates that the plaintiff was represented by independent counsel during negotiations involving the parties’ prenuptial agreement, that she signed the agreement, and that her counsel signed the agreement as a witness. Moreover, the agreement itself recites that the wife entered into it “freely, voluntarily and with full knowledge of all circumstances having a bearing on this agreement.” Although the plaintiff would receive, in the event of a divorce, equitable distribution of the marital assets in an amount no greater than the sum of $25,000 per year for each full year the parties had been married, she was provided with meaningful bargained-for benefits, including a one-third interest in one of the defendant’s businesses. In opposition to the defendant’s prima facie showing of his entitlement to judgment as a matter of law, the plaintiff advanced nothing but conclusory and unsubstantiated assertions insufficient to defeat a motion for summary judgment (see Piccone v Chamberlain, 271 AD2d 667 [2000]; see generally Alvarez v Prospect Hosp., 68 NY2d 320, 326 [1986]). Accordingly, the Supreme Court properly granted that branch of the defendant’s motion which was for summary judgment dismissing the sixth cause of action to set aside the parties’ prenuptial agreement on the ground of unconscionability (see Schultz v Schultz, 58 AD3d 616, 617 [2009]; Valente v Valente, 269 AD2d 389, 390 [2000]).

The plaintiffs remaining contentions are without merit (see Weinstein v Weinstein, 36 AD3d 797, 799 [2007]; Piccone v Chamberlain, 271 AD2d at 667; Yedvarb v Yedvarb, 237 AD2d 433, 434 [1997]; Panossian v Panossian, 172 AD2d 811 [1991]). Rivera, J.P., Angiolillo, Balkin and Leventhal, JJ., concur.

In an action, inter alia, to set aside a prenuptial agreement, the defendant appeals, as limited by his brief, from so much of a *767judgment of the Supreme Court, Nassau County (Bennett, J.), entered February 6, 2012, as, upon a decision of the same court (Falanga, J.), dated December 12, 2011, made after a nonjury trial, is in favor of the plaintiff and against him setting aside the prenuptial agreement.

Ordered that the judgment is affirmed insofar as appealed from, with costs.

In general, New York has a “strong public policy favoring individuals ordering and deciding their own interests through contractual arrangements” (Matter of Greiff, 92 NY2d 341, 344 [1998]; see Bloomfield v Bloomfield, 97 NY2d 188, 193 [2001]). “However, this right is not and has never been without limitation” (Kessler v Kessler, 33 AD3d 42, 45 [2006]). “[T]he State is deeply concerned with marriage and takes a supervisory role in matrimonial proceedings. . . . Indeed, in numerous contexts, agreements addressing matrimonial issues have been subjected to limitations and scrutiny beyond that afforded contracts in general” (id. at 46 [citation omitted]). Thus, while “there is a heavy presumption that a deliberately prepared and executed written instrument manifests the true intention of the parties” (Brassey v Brassey, 154 AD2d 293, 295 [1989]), an agreement between spouses or prospective spouses may be invalidated if the party challenging the agreement demonstrates that it was the product of fraud, duress, or other inequitable conduct (see Christian v Christian, 42 NY2d 63, 73 [1977]; Petracca v Petracca, 101 AD3d 695 [2012]; Weinstein v Weinstein, 36 AD3d 797, 798 [2007]; Lombardi v Lombardi, 235 AD2d 400 [1997]).

“In reviewing a trial court’s findings of fact following a nonjury trial, this Court’s authority is as broad as that of the trial court and includes the power to render the judgment it finds warranted by the facts, bearing in mind that due regard must be given to the decision of a trial judge who was in the position to assess the evidence and the credibility of witnesses” (D’Argenio v Ashland Bldg., LLC, 78 AD3d 758, 758 [2010]).

Here, the Supreme Court reasonably resolved credibility issues in favor of the plaintiff, and its determination that the defendant fraudulently induced the plaintiff to execute the prenuptial agreement was supported by the evidence. With respect to the material facts underlying the plaintiff’s claim, the Supreme Court found that the plaintiffs testimony was “credible,” “convincing,” “unequivocal,” and consistent with “additional corroborative evidence,” and that any “inconsistencies” in her testimony related to “insignificant” matters. By contrast, the Supreme Court found the defendant’s “credibility to be suspect,” due in part, to his “patent evasiveness.” The Supreme *768Court’s credibility findings are supported by the record. The plaintiffs claim in this case rested largely on the credibility of the parties, and we decline to disturb the Supreme Court’s determination with respect thereto (see Reid v Reid, 57 AD3d 960 [2008]). On the particular facts of this case, the Supreme Court correctly determined that the plaintiff sustained her burden of establishing grounds to set aside the prenuptial agreement (cf. Petracca v Petracca, 101 AD3d at 695).

The defendant’s remaining contentions are without merit. Angiolillo, J.P., Sgroi, Cohen and Miller, JJ., concur.

The parties were married on December 16, 1995. In March 1996, the parties entered into a postnuptial agreement. The agreement provided that the jointly owned marital residence, which had been purchased for approximately $3.1 million after the parties were married, and which was subsequently renovated *696at a cost of between $3 million and $5 million, was the defendant’s separate property.

The agreement further provided that if the parties divorced, the plaintiff, who had not been employed other than as a homemaker since October 1995, would waive her interest in any business in which the defendant had an interest, including any appreciation in the value of such interests accruing during the marriage. At the time the agreement was entered into, the defendant valued his interests in these business entities at over $10 million. The plaintiff also waived any and all rights she had to the defendant’s estate, including her right to an elective share. At the time the agreement was entered into, the defendant valued his net worth at more than $22 million.

Finally, the agreement provided that if the parties divorced, the plaintiff would waive any right to maintenance except as provided in schedule “C” of the agreement, which indicated that the plaintiff could receive maintenance in the sum of between $24,000 and $36,000 per year, for varying lengths of time, depending on the duration of the marriage. The defendant’s obligation to pay the limited maintenance enumerated in the agreement was contingent upon his receipt of certain visitation with any children that the parties might have, and upon certain residency requirements imposed upon the plaintiff.

In 2008, the plaintiff commenced this action, inter alia, for a divorce on the ground of constructive abandonment. In his answer, the defendant, among other things, sought enforcement of the postnuptial agreement. The defendant subsequently moved for a protective order in response to the plaintiff’s discovery demands, and the plaintiff cross-moved to set aside the postnuptial agreement.

A hearing was held at which both parties testified. The plaintiff testified that the defendant had presented the postnuptial agreement to her for signature days after her 42nd birthday, and shortly after she had suffered a miscarriage. She testified that the defendant had “bullied” her into signing the agreement by threatening that they would not have any children and that the marriage would be over if she did not consent to the postnuptial agreement. The plaintiff testified that she and the defendant had agreed to have children prior to the marriage, and that their agreement to have children had been an important factor in her decision to marry him. She signed the agreement within days of receiving it and, although she reviewed some portions of it, she did not understand its terms and did not consult an attorney. The plaintiff also adduced evidence demonstrating that the statement of the defendant’s net *697worth contained in the agreement was inaccurate at the time it was made in that it was undervalued by at least $11 million.

When the defendant testified, he denied any knowledge of the plaintiffs miscarriage and stated that he had wanted the post-nuptial agreement in order to protect his son from a prior marriage. The defendant testified that the parties had discussed the issue of entering into a postnuptial agreement prior to the marriage and that they had negotiated the postnuptial agreement over the course of many weeks. The defendant testified that his attorney had drafted the agreement and that he believed that the plaintiff had consulted with her own attorney, although she had not disclosed her attorney’s name to him. The defendant explained that the marital residence had been purchased in both parties’ names because the plaintiff said she wanted to have her name on it “for perception purposes, for other people,” but that she had been willing to sign the agreement converting it into the defendant’s separate property shortly after its purchase.

In a decision made after the hearing, the Supreme Court expressed doubts as to the defendant’s veracity and credited the plaintiffs testimony over conflicting portions of the defendant’s testimony. The court found that the plaintiff had not been represented by counsel and had been precluded from effectively-analyzing the financial impact of the postnuptial agreement due to the inaccuracies contained in the financial disclosures that had been incorporated into the agreement. The court determined that the terms of the agreement were “wholly unfair” and, after examining the totality of the circumstances, concluded that it was unenforceable. In a subsequent order, made upon the decision, the court granted the plaintiffs cross motion to set aside the postnuptial agreement.

In general, a postnuptial agreement “which is regular on its face will be recognized and enforced by the courts in much the same manner as an ordinary contract” (Levine v Levine, 56 NY2d 42, 47 [1982]; see Rauso v Rauso, 73 AD3d 888, 889 [2010]; Cioffi-Petrakis v Petrakis, 72 AD3d 868, 869 [2010]; Whitmore v Whitmore, 8 AD3d 371, 372 [2004]). However, “[agreements between spouses, unlike ordinary business contracts, involve a fiduciary relationship requiring the utmost of good faith” (Christian v Christian, 42 NY2d 63, 72 [1977]; see Matter of Greiff, 92 NY2d 341, 345 [1998]; O'Malley v O'Malley, 41 AD3d 449, 451 [2007]; Manes v Manes, 277 AD2d 359, 361 [2000]). Accordingly, “courts have thrown their cloak of protection” over postnuptial agreements, “and made it their business, when confronted, to see to it that they are arrived at *698fairly and equitably, in a manner so as to be free from the taint of fraud and duress, and to set aside or refuse to enforce those born of and subsisting in inequity” (Christian v Christian, 42 NY2d at 72; see Infante v Infante, 76 AD3d 1048, 1049 [2010]).

Because of the fiduciary relationship between spouses, post-nuptial agreements “are closely scrutinized by the courts, and such agreements are more readily set aside in equity under circumstances that would be insufficient to nullify an ordinary contract” (Levine v Levine, 56 NY2d at 47; see Kabir v Kabir, 85 AD3d 1127, 1127 [2011]; Manes v Manes, 277 AD2d at 361; Cardinal v Cardinal, 275 AD2d 756, 757 [2000]). “To warrant equity’s intervention, no actual fraud need be shown, for relief will be granted if the [agreement] is manifestly unfair to a spouse because of the other’s overreaching” (Christian v Christian, 42 NY2d at 72-73; see Infante v Infante, 76 AD3d at 1049; OMalley v OMalley, 41 AD3d at 451; Frank v Frank, 260 AD2d 344, 345 [1999]; see also Levine v Levine, 56 NY2d at 47).

In determining whether a postnuptial agreement is invalid, “courts may look at the terms of the agreement to see if there is an inference, or even a negative inference, of overreaching in its execution” (Christian v Christian, 42 NY2d at 73; see Terio v Terio, 150 AD2d 675, 675-676 [1989]; Stern v Stern, 63 AD2d 700, 700-701 [1978]). A spouse seeking to set aside a postnuptial agreement initially “bears the burden to establish a fact-based, particularized inequality” (Matter of Greiff, 92 NY2d at 346; see Matter of Barabash, 84 AD3d 1363, 1364 [2011]; D’Elia v D’Elia, 14 AD3d 477, 478-479 [2005]; accord Brennan-Duffy v Duffy, 22 AD3d 699, 700 [2005]; Chambers v McIntyre, 5 AD3d 344, 345 [2004]). Where this initial burden is satisfied, a proponent of a postnuptial agreement “suffers the shift in burden to disprove fraud or overreaching” (Matter of Greiff, 92 NY2d at 346; see Matter of Barabash, 84 AD3d at 1364; D’Elia v D’Elia, 14 AD3d at 478-479).

Here, the plaintiff demonstrated that the terms of the post-nuptial agreement were manifestly unfair given the nature and magnitude of the rights she waived, particularly the relinquishment of her property rights in the marital residence and her waiver of all of her inheritance rights, in light of the vast disparity in the parties’ net worth and earnings (see Manes v Manes, 277 AD2d at 361; Frank v Frank, 260 AD2d at 345; Terio v Terio, 150 AD2d at 675-676; Stern v Stern, 63 AD2d at 700-701; see also O’Malley v O’Malley, 41 AD3d at 451; Pisano v Pisano, 71 AD2d 670, 670 [1979]; cf. Levine v Levine, 56 NY2d at 47). Furthermore, inasmuch as the terms of the agreement were manifestly unfair to the plaintiff and were unfair when the *699agreement was executed, they give rise to an inference of overreaching (see Christian v Christian, 42 NY2d at 73; Terio v Terio, 150 AD2d at 675-676; Stern v Stern, 63 AD2d at 700-701). This inference of overreaching is bolstered by the evidence submitted by the plaintiff, including her testimony, regarding the circumstances which led her to give her assent to the post-nuptial agreement (see Kabir v Kabir, 85 AD3d at 1127; Cardinal v Cardinal, 275 AD2d at 757; Terio v Terio, 150 AD2d at 675-676). The defendant’s testimony which tended to show that he did not engage in overreaching raised an issue of credibility, and we decline to disturb the Supreme Court’s determination with respect thereto (see Northern Westchester Professional Park Assoc. v Town of Bedford, 60 NY2d 492 [1983]; Reid v Reid, 57 AD3d 960 [2008]).

The defendant’s remaining contentions are without merit.

Accordingly, the Supreme Court properly granted the plaintiffs cross motion to set aside the parties’ postnuptial agreement. Eng, P.J., Florio, Sgroi and Miller, JJ., concur.

Cooke, J.

Marriage being a status with which the State is deeply concerned, separation agreements subjected to attack are tested carefully. "A court of equity does not limit its inquiry to the ascertainment of the fact whether what had taken place would, as between other persons, have constituted a contract, and give relief, as a matter of course, if a formal contract be established, but it further inquires whether the contract [between husband and wife] was just and fair, and equitably ought to be enforced, and administers relief where both the contract and the circumstances require it” (Hen*66dricks v Isaacs, 117 NY 411, 417; Hungerford v Hungerford, 161 NY 550, 553).

We review here the grant by the Appellate Division of a divorce to one spouse, because of a living separate and apart by the marital parties pursuant to a separation agreement as provided by statute (Domestic Relations Law, § 170, subd [6]), and, more particularly, the declaration that a portion of the agreement, which stipulated that there be an equal division of certain securities, was null and void.

Henrietta Christian and William Christian were married in 1958. Five years later a daughter was born and, about two years thereafter, a son. The husband, the holder of a degree in mechanical engineering, was the vice-president in charge of manufacturing for a metal fabricating concern. The wife in time had acquired a master’s degree in social work and held a position at a school for girls. Unfortunately, differences arose and, following a bit of marriage counseling, they entered into a separation agreement on January 15, 1972. At that time, the husband’s employment earnings were $40,000 a year and the wife’s $10,000. In addition, both also had separate unearned income.

The agreement contained a section numbered "6”, entitled "Division of Property”. In it, provisions were made with reference to such items as the family residence, automobiles, household furnishings, hospital, medical and dental care policies and life insurance. The section concluded with the paragraph: "During the period of the separation assets held in individual name shall continue to be so held and all joint assets shall continue to be held jointly. In the event that the parties are divorced all assets held by the parties in their joint and individual names on January 1, 1972, a list of which properties is appended hereto as Schedule A, shall be divided equally between the parties so that the Husband shall take one-half of all assets held by the Wife in her individual name on January 1, 1972 and she shall take one-half of all assets held by the Husband on that date. It is the intent of the parties that so far as economic circumstances of the parties permit the money which each receives from the other shall be preserved and left by Will to the two children, Christine and Keith.” No mention was made of support of the wife, but the husband covenanted to pay $100 a week for the children.

This action was commenced in August of 1972 by the plaintiff wife for divorce on the ground of cruel and inhuman *67treatment, pursuant to subdivision (1) of section 170 of the Domestic Relations Law. The defendant, in the following January, served an amended answer containing a counterclaim for divorce predicated on the living separate and apart by the parties since the execution of the separation agreement, a period in excess of one year, and the due performance by defendant of all of the agreement’s terms and conditions. The answer also prayed that the separation agreement be incorporated but not merged in the judgment and for such other relief as would be just. For her reply, plaintiff denied the essential allegations of the counterclaim and asserted affirmative defenses to the effect that the agreement was procured as a result of fraud, misrepresentations and concealment, was the product of coercion and duress, was made without consideration and violated public policy.

During a nonjury trial, plaintiff’s complaint was dismissed for failure to make out a prima facie case. Following full submission of proof, Supreme Court declared the separation agreement null and void for fraud, set it aside in its entirety, dismissed the husband’s counterclaim, and ordered the parties to co-operate to effect a reconciliation and resumption of the marital relationship. The last paragraph of section "6” of the agreement was examined. Noting that the husband was aware that his stocks listed in the schedule were worth’$200,000 while those of the wife had a value of $800,000 to $900,000, that the wife contended that she had no idea of the relative values of the securities, that the husband cleverly maneuvered the retention of the attorney who ostensibly represented the wife and drew the agreement, that neither party informed the attorney of the values of the stock being split, it was concluded that the husband’s conduct in procuring the drafting of the agreement and in concealing from the attorney the details of the distribution of assets constituted such fraud as to vitiate the agreement completely.

The Appellate Division unanimously reversed, on the law and the facts, granted defendant husband’s counterclaim for divorce and declared the last paragraph of provision "6” of the parties’ agreement null and void. It was held that the record did not support Supreme Court’s findings of fact to the effect that defendant was guilty of fraud or overreaching with regard to the formulation or signing of the agreement, that plaintiff failed to sustain her burden of proof as to her affirmative defense of fraud in the inducement. Insofar as the *68parties had lived separate and apart pursuant to the agreement, properly executed and filed, and adhered to its terms for more than a year, thus fulfilling the statutory requirements, defendant was held to be entitled to a decree of divorce. In the Appellate Division’s view, the wife was not represented by an attorney acting solely in her interests and her knowledge of financial matters was not equal to that of her husband. In the light of these facts, the relative value of the listed securities to be divided and the high price plaintiff apparently was prevailed upon to pay for her husband’s signature to the separation agreement, the last paragraph of provision "6” was held to be so unconscionable as to be unenforceable.

With the enactment of the Divorce Reform Law of 1966 (L 1966, ch 254), New York abandoned its position as the only State in the union which regarded adultery as the sole ground for absolute divorce. Under a new section 170 of the Domestic Relations Law, an action for divorce may be maintained on any one of six grounds, including adultery, the scope of which was extended by definition (subd [4]). Cruel and inhuman treatment, abandonment and imprisonment were joined as bases for the action (subds [1], [2], [3]). Finally, under the last two subdivisions, two new grounds for absolute divorce were specified—living apart pursuant to a separation decree or judgment and living separate and apart pursuant to a written separation agreement (subds [5], [6]).

These last two bases have become known as the "no fault” grounds, since they were designed to make separation a ground for divorce, regardless of fault, as long as the authenticity of the separation is supported by a separation decree or agreement (see Foster & Freed, Matrimonial Law [rev ed, 1973], p 29).1 "The decree [or agreement] is simply intended as evidence of the authenticity and reality of the separation” (Gleason v Gleason, 26 NY2d 28, 35). This requirement as to a separation decree or agreement is peculiar to New York and reflects legislative concern over the fraud and collusion which historically infected divorce actions involving adultery. At the 1966 legislative session, the original broad proposal for a "living separate and apart” ground, as incorporated in the Wilson-Sutton Bill, at first rejected in the so-called "Leader’s *69Bill”, was finally incorporated in the compromise bill, conditioned on the requirements that there be a formal and filed written agreement and that the party seeking to come within the embrace of such ground prove that "he or she has duly performed all the terms and conditions of such agreement”2 (1 Foster & Freed, Law and the Family, pp 264, 333, n 9; p 337; Foster & Freed, The Divorce Law Reform [1970], p 22; see Littlejohns v Littlejohns, 76 Misc 2d 82, 86, affd on opn at Trial Term 42 AD2d 957).

Divorces provided for in subdivisions (5) and (6) are also referred to as "conversion” divorces in that they permit the conversion of a judicial separation decree or separation agreement into an absolute divorce decree. In Gleason, an action under subdivision (5), it was held that "the statute, as a whole, points [to] the construction that all that has to be proved is that there is some kind of formal document of separation * * * that the plaintiff has complied with its terms and that the parties have lived apart” pursuant to the document for the statutory period (p 37).

It was the legislative intent to provide these nonfault grounds for divorce where marriages are dead, based on a recognition that it was morally and socially desirable, to society and to the parties to such a union, to enable them " 'to extricate themselves from a perpetual state of marital limbo’ ” (Gleason v Gleason, 26 NY2d 28, 35, 37, supra). The "vital and operative” fact, in subdivision (6) divorce cases, is the actual living apart of the parties—pursuant to the separation agreement (cf. id., p 37). Put a bit differently, the function of the document is "merely to authenticate the fact of separation” (cf. id., p 37). Once there has been a separation for one or more years (L 1970, ch 835, § 2) supported by the prescribed separation agreement with which there has been substantial compliance, the statute suggests no condition or restriction on the right of either party to commence the action (see Tantleff v Tantleff, 60 Misc 2d 608, 611, affd on limited grounds 33 AD2d 898). A number of decisions, following in the wake of the 1966 reforms, have held that even though individual clauses in a separation agreement were void, the agreement supplied grounds for divorce under subdivision (6) of section 170 of the Domestic Relations Law since such agreements survive for that purpose (see, e.g., Bruno v Bruno, 51 AD2d *70862, mot for lv to app den 39 NY2d 706; Seligman v Seligman, 78 Misc 2d 632, 635; Hummel v Hummel, 62 Misc 2d 595, 599; but see Markowitz v Markowitz, 77 Misc 2d 586, 589, 592).

The cause of action in defendant’s counterclaim is one for divorce under subdivision (6) of section 170, and the reply thereto asserts affirmative defenses. No cause is set forth by either party for enforcement or invalidation of the separation agreement. As to said counterclaim, it is the physical separation, rather than the writing, which constitutes the actual basis of the cause (Littlejohns v Littlejohns, 76 Misc 2d 82, 86, affd on opn at Trial Term 42 AD2d 957, supra; Hummel v Hummel, 62 Misc 2d 595, 599, supra). The agreement is "simply intended as evidence of the authenticity and reality of the separation” (cf. Gleason v Gleason, supra, p 35; Harris v Harris, 36 AD2d 594; see Martin v Martin, 63 Misc 2d 530, 533). In Littlejohns the agreement was viewed as evidence of the parties’ actual and continued separation (p 86), and, in Markowitz, the instrument was said to be "merely documentary proof of a separation” (p 591). In Martin, a stipulation made in open court, the transcript of which was filed with the County Clerk, was held to carry no less weight than a written agreement, since the purpose of the filing provision in respect to separation agreements is to evidence the fact that the agreement was made before maintenance of the divorce action (but see Nitschke v Nitschke, 66 Misc 2d 435, 436-437; Jacobs v Jacobs, 55 Misc 2d 9).

Although a written separation agreement is a sine qua non to a divorce under subdivision (6), it is evidentiary in nature and admissible under general rules of evidence (see Richardson, Evidence [Prince—10th ed], § 643). By the same token, proof independent of the agreement would also be admissible on the question of whether or not the parties actually lived separate and apart for at least one year. Therefore, if the separation agreement conforms to the statute but is otherwise found to be void and unenforceable insofar as its substantial provisions are concerned, generally it may still be accepted for the sole purpose of evidencing the parties’ agreement to live separate and apart, thus satisfying the statutory requirement in respect to a separation agreement (see Henderson v Henderson, 47 AD2d 801, app dsmd 37 NY2d 782; 11A Zett-Edmonds-Schwartz, NY Civ Prac, Matrimonial Actions, § 21.05, p 21-14; see, also, La Barge v La Barge, 84 Misc 2d 523, 524-525; but see Cicerale v Cicerale, 85 Misc 2d 1071, 1075). In this *71same vein, it was held, long before 1966, in Reischneld v Reischneld (100 Misc 561), an action for separation based on abandonment and other grounds, that, even though void, a separation agreement negated an abandonment since the husband and wife separated voluntarily (see Matter of Brown, 153 Misc 282, 284; 16 NY Jur, Domestic Relations, § 886; see, also, Rosenbaum v Rosenbaum, 56 Misc 2d 221, 224). Since, as the Appellate Division here stated, "[t]he parties have lived separate and apart from each other pursuant to their agreement, which was properly executed and filed, and each has adhered to the terms thereof for a period of more than one year”, the requirements of subdivision (6) were fulfilled and that court properly granted a divorce on the counterclaim.

Said court was of the view, however, that the portion of the agreement which called for an equal division of the assets listed in the annexed schedule was "so unconscionable as to be unenforceable” and that the wife should not be required to pay such substantial sums to her husband "upon the advent of such divorce in compliance with a portion of the separation agreement which is tainted with unconscionability” citing Riemer v Riemer (48 Misc 2d 873, affd 25 AD2d 956, mot for lv to app dsmd 17 NY2d 915). In Riemer the word "unconscionable” does not appear, but, over the years, an unconscionable bargain has been regarded as one " 'such as no [person] in his [or her] senses and not under delusion would make on the one hand, and as no honest and fair [person] would accept on the other’ ” (Hume v United States, 132 US 406, 411), the inequality being " 'so strong and manifest as to shock the conscience and confound the judgment of any [person] of common sense’ ” (Mandel v Liebman, 303 NY 88, 94). Unconscionable conduct is something of which equity takes cognizance, when warranted (see Weirfield Holding Corp. v Pless & Seeman, 257 NY 536; Graf v Hope Bldg. Corp., 254 NY 1, 4; Howard v Howard, 122 Vt 27; 27 Am Jur 2d, Equity, § 24, pp 549-550; cf. 2 Pomeroy’s Equity Jurisprudence [4th ed], § 873, p 1804).

Generally, separation agreements which are regular on their face are binding on the parties, unless and until they are put aside (2 Foster & Freed, Law and the Family, p 476; see, also, Schmelzel v Schmelzel, 287 NY 21, 26; 2 Lindey, Separation Agreements and Ante-Nuptial Contracts [rev ed], § 36, subd 1, p 36-3). Judicial review is to be exercised circumspectly, sparingly and with a persisting view to the encouragement of parties settling their own differences in connection *72with the negotiation of property settlement provisions. Furthermore, when there has been full disclosure between the parties, not only of all relevant facts but also of their contextual significance, and there has been an absence of inequitable conduct or other infirmity which might vitiate the execution of the agreement, courts should not intrude so as to redesign the bargain arrived at by the parties on the ground that judicial wisdom in retrospect would view one or more of the specific provisions as improvident or one-sided.

If voidable, such an agreement may be set aside under principles of equity in an action in which such relief is sought in a cause of action or by way of affirmative defense (Susquehanna S. S. Co. v Andersen & Co., 239 NY 285, 292-294; 16 NY Jur, Domestic Relations, § 715). Agreements between spouses, unlike ordinary business contracts, involve a fiduciary relationship requiring the utmost of good faith (Ducas v Guggenheimer, 90 Misc 191, 194-195, affd sub nom. Ducas v Ducas, 173 App Div 884). There is a strict surveillance of all transactions between married persons, especially separation agreements (Hendricks v Isaacs, 117 NY 411, 417, supra; Benesch v Benesch, 106 Misc 395, 402; 2 Lindey, Separation Agreements and Ante-Nuptial Contracts [rev ed], § 37, subd 4, p 37-9). Equity is so zealous in this respect that a separation agreement may be set aside on grounds that would be insufficient to vitiate an ordinary contract (Hungerford v Hungerford, 161 NY 550, 553, supra; Cain v Cain, 188 App Div 780, 782; Crowell v Crowell, 135 Misc 530, 532, affd 229 App Div 771). These principles in mind, courts have thrown their cloak of protection about separation agreements and made it their business, when confronted, to see to it that they are arrived at fairly and equitably, in a manner so as to be free from the taint of fraud and duress, and to set aside or refuse to enforce those born of and subsisting in inequity. (Scheinberg v Scheinberg, 249 NY 277, 282-283; Hungerford v Hungerford, 161 NY 550, 553, supra; Matter of Smith, 243 App Div 348, 353; Ducas v Guggenheimer, 90 Misc 191, 194, affd sub nom. Ducas v Ducas, 173 App Div 884, supra; Montgomery v Montgomery, 170 NYS 867, affd 187 App Div 882; see Validity of Separation Agreement As Affected by Fraud, Coercion, Unfairness or Mistake, Ann., 5 ALR 823, 827).

To warrant equity’s intervention, no actual fraud need be shown, for relief will be granted if the settlement is manifestly unfair to a spouse because of the other’s overreaching (2 *73Lindey, Separation Agreements and Ante-Nuptial Contracts [rev ed], § 37, subd 5, p 37-12; cf. Matter of Baruch, 205 Misc 1122, 1124, affd 286 App Div 869; Pegram v Pegram, 310 Ky 86, 89-90). In determining whether a separation agreement is invalid, courts may look at the terms of the agreement to see if there is an inference, or even a negative inference, of overreaching in its execution. If the execution of the agreement, however, be fair, no further inquiry will be made.

Whether a contract is entire or severable generally is a question of intention, to be determined from the language employed by the parties, viewed in the light of the circumstances surrounding them at the time they contracted (5 Williston, Contracts [3d ed], § 767, p 629). Here the parties had a right to and did, by expressly stipulating that if any provision of the separation agreement be held invalid or unenforceable all other shall nevertheless continue in full force, make the agreement within reasonable limits divisible, and there is little room for construction (New Era Homes Corp. v Forster, 299 NY 303, 306-307; Coppedge v Leiser, 71 Idaho 248, 251-253; see United States v Bethlehem Steel Corp., 315 US 289, 298). Courts were therefore, by contract terms, free to adjudge the validity of the last paragraph of provision "6” of the separation agreement without consequential effect on the remainder of the writing.

This case is of moment. Important it is, because separation agreements have assumed a new and greater legal dimension. Not only may they serve as "evidence of the authenticity and reality of the separation” which is a basis for absolute divorce but, even though a portion of the agreement, such as one dealing with the economics or property of the marital parties, be declared void because of overreaching in bringing about its execution, the separation agreement still retains vitality as an essential ingredient in such an action for dissolution of the marriage. Because of the law’s purpose, to achieve its moral and social goals and to avoid a frustration of those aims, separation agreements must not be permitted to be employed as instruments for the improper exaction in the inducement of execution of unconscionable terms within a frame of inequitable conduct.

The order of the Appellate Division, insofar as appealed from, should be reversed, without costs, and the case remitted to the Supreme Court, Suffolk County, for further proceedings *74including a hearing and findings as may be appropriate in accordance with this opinion.

Chief Judge Breitel and Judges Jasen, Gabrielli, Jones, Wachtler and Fuchsberg concur.

Order, insofar as appealed from, reversed, without costs, and the case remitted to Supreme Court, Suffolk County, for further proceedings in accordance with the opinion herein.