If you sign a Will under “undue influence,” that Will is invalid.
What, then, is “undue influence.” Much like the concept of “testamentary capacity,” the concept of “undue influence” is difficult to define because it is dependent on an evaluation of the unique facts and circumstances of each case.
Most obviously, the term “undue influence” encompasses things like duress and fraud. If someone forces you to sign a Will at gunpoint, you will have signed that Will under duress. Or, if someone tricked you into signing a Will by fraudulently representing to you that you were signing a different kind of document, you have been fraudulently induced to sign. In both cases, undue influence has occurred, and the Will is invalid. Undue influence doesn’t need to be that overt, though. It can occur subtly. For example, a doctor might gently manipulate an elderly patient to amend his or her Will over the course of inpatient treatment. There has been no violence or fraud, but such manipulation would give rise to undue influence and hence an invalid Will.
Again, like so many other concepts that apply to Will contests, it is difficult to define because of the multitude of potential fact patterns that could exist.
Ultimately, a Will is invalid if it was improperly executed, if the Testator did not have testamentary capacity, or if the Testator had been unduly influenced. Among others, these concepts form the legal groundwork upon to establish a successful Will contest.