Undue influence occurs when an individual is able to persuade another's decisions due to the relationship between the two parties. Often, one of the parties is in a position of power over the other due to elevated status, higher education, or emotional ties. The more powerful individual uses this advantage to coerce the other individual into making decisions that might not be in their long-term best interest.

Undue influence is an equitable doctrine that involves one person taking advantage of a position of power over another person.