Fraud, duress and undue influence commonly shortened to simply "undue influence," is statistically the most frequent basis for blocking probate of a will or enforcement of a trust. It can also result in partial invalidity if the remainder of the document is not invalid for other reasons. Simply stated, it is the substitution of another person's will for that of the testator or trustmaker.
A frequent scenario in such cases is this: A family member or caretaker brings in an elderly client, stays with the client during the planning meeting, may even pay for the attorney's or other professional's services, and becomes the main beneficiary or heir. The beneficiary may or may not be related to the client.
When a court makes a determination of whether undue influence has been exercised, it considers a variety of factors, including whether the transaction took place at an appropriate time and in an appropriate setting, and whether the testator was pressured into acting quickly or discouraged from seeking advice from others. Courts also consider the relationship between the parties and the "fairness" of the transaction.