Undue influence occurs when one party in a relationship dominates the will of the other party to obtain an unfair advantage. For a contract to be affected by undue influence, there must be a relationship where one party can dominate the other, the dominant party must intend to take unfair advantage, and they must use their position to influence the other's decision. Certain relationships like parent-child or trustee-beneficiary are considered fiduciary and undue influence is presumed, while influence must be proven in other relationships like husband-wife. Undue influence differs from coercion in that it uses moral pressure rather than physical force and requires a relationship where one party can dominate the other. A contract induced by undue influence may be considered voidable