necessitas culpabilis (n<<schwa>>-ses-i-tas k<<schwa>>l-pay-b<<schwa>>-lis). [Latin “culpable necessity”] Hist. An unfortunate necessity that, while essentially excusing the act done under its compulsion, does not necessarily relieve the actor from blame.

“And as to the necessity which excuses a man who kills another se defendendo lord Bacon entitles it necessitas culpabilis …. For the law intends that the quarrel or assault arose from some unknown wrong … and since in quarrels both parties may be, and usually are, in some fault; and it scarce can be tried who was originally in the wrong; the law will not hold the survivor entirely guiltless. But it is clear, in the other case, that where I kill a thief that breaks into my house, the original default can never be upon my side.” 4 William Blackstone, Commentaries on the Laws of England 186–87 (1769).

[Blacks Law 8th]