Legal Definition of Undue influence: An improper amount of pressure which influences someone to do something he would not do if left to his own devices. As an example, if it can be proved that someone persuaded a maker of a will to leave him money that he would not have received except for his undue influence, then the will might be set aside and nullified | Learn about undue influence in legal terms and its significance. Find out how it can affect individuals and businesses, and the potential consequences. Discover examples of undue influence and understand your rights if you suspect you’ve been subjected to it. Protect yourself and make informed decisions with this essential knowledge. Seek legal advice promptly if needed