Lawsuits are expensive and unwieldy. They take a lot of time – years, even. They are emotionally draining, sometimes devastating – even for winners. And a court and its enforcement mechanisms may not be available in an exigently-unfolding situation. In light of this, the law might contemplate that private actors faced with perceived wrongdoing might be given license to take matters into their own hands. Recognizing the defense of self-defense in battery is one way that the law understands that it can be better, or at least acceptable, for people to help themselves. What about less dire situations than defense of life or bodily integrity? Is it OK to chase after someone who has stolen something? To set a trap on one’s own property to deter or incapacitate wrongdoers, especially if the trap is only sprung against people who are manifestly in a place where they have no permission to be? How much should barriers to effective legal enforcement grant license to individual action, even vigilantism? This section’s cases look at these questions through some classic formulations – a spring-gun, for example – and through some more recent ones: the problems arising from spam. In the latter case, we look both at how this new and vexing phenomenon might be worked into the canon of tort, in particular, trespass to chattel, and also how the law should view acts of self-help taken against spammers.