Use of legal terms in will contests: implications for psychiatrists.

This article reviews legal concepts involved in challenges to wills and how wills are influenced by psychiatric testimony. The outcome of litigation in certain landmark cases and in cases from the extensive experience of the first author is discussed. Clarifications of legal terms of art such as "lucid interval," "testamentary capacity," "undue influence," and "insane delusion" are offered. Pre-death psychiatric evaluations are becoming increasingly important in an aging population more susceptible to mental impairment.