Undue influence (UI) is a psychological process by which a person's free will and judgement is supplanted by that of another. It is a legal term and the strict definition varies by jurisdiction.

Undue influence is typically perpetrated by a person who is trusted by the victim and is dependent on them for emotional and physical needs. UI is a process, not a single event. A manipulator may spend weeks, months, or even years before successfully unduly-influencing their victim. Modern families are becoming more complex and dispersed. Given these factors, the number of will contests involving undue influence is expected to increase.

  • Terminal diagnosis – Being diagnosed with a terminal illness such as cancer typically causes the victim to experience stress and trauma which increases their susceptibility.
  • Depression – The effects of depression are pernicious and contribute to a person becoming predisposed to undue influence.
  • Dependency – When a victim is dependent upon the influencer for companionship, transportation, housekeeping, food, hydration, medicine, etc.
  • Diminished mental capacity – Mental function declines, particularly as a result of aging. A person having difficulty thinking clearly may look to another to think things through for them.
  • Substance use – Illicit drugs, alcohol, or prescribed medication may alter a person's judgment. Drugs can also cause addiction, and the influencer may leverage the addiction to control the person. The influencer may refuse to give the addicted person their pain medication unless the victim does things for the influencer they wouldn't normally do.
  • Recent bereavement – The death of a family member such as a spouse or child.

Tactics

A person seeking to exert undue influence on another person usually does so by leveraging their position of apparent authority.

  • Moving into the victims' home, changes in victim's spending habits, unexplained purchases, and/or using victims' credit cards.
  • Controlling the flow of information to manipulate the victim and their view of the world. Statements such as - "Your children aren't even around", "I'm the only one that's here for you, nobody else cares" or, "your friends are only coming around because they want to take advantage of you", are examples of relationship poisoning.

Lawsuits against estate planning attorneys have increased in recent years. Experienced estate attorneys tend to be vigilant of "red flags" indicative of undue influence during the drafting and execution of a will. Access to the individual is typically controlled by the influencer so that friends and family are unable to observe the perpetrator engaging in manipulation, thus a challenger is often unable to provide direct evidence. In an effort to address this substantial power distinction, many states allow for the burden of proof to be shifted to the alleged influencer if certain requirements are satisfied.

Once shifted, the proponent of the contested will is tasked with rebutting the presumption. The study revealed similarities in persons who were particularly susceptible to unduly influence such as:

  • Vulnerability of the victim - Age, weakened physical or mental state.
  • Dependency - Reliant on the influencer.
  • Isolation - The victim may live alone or in a remote area, suffering from family conflict or having no living relatives.