The principle is now fully recognized in this country that a "person who has been unjustly enriched at the expense of another is required to make restitution to the other." This is the language of the first section of the Restatement of Restitution.' When one person confers a benefit upon another without the latter's solicitation, the benefit received constitutes an enrichment--a windfall, so to speak. This benefit may take one of several forms. It may involve (1) transferring property to the defendant, (2) saving, preserving or improving his property, (3) rendering personal services for him, or (4) performing for him a duty imposed directly by law or by his own contractual arrangements. In any of these situations there is an enrichment,and the principle quoted above comes into play if the enrichment is"unjust." When is it unjust? Obviously, it would not be so characterized if it were intended as a gift; just as obviously, the opposite is true if the plaintiff acted under legal compulsion and against his will. In making the determination, considerable weight is given to the circumstance that the benefit was not requested by the defendant. The common law has long had a pronounced policy that benefits may not be forced upon a party against his will, so as to require him to pay for them. This idea has been forcefully expressed on a number of occasions.
John W. Wade,
Restitution for Benefits Conferred Without Request,
19 Vanderbilt Law Review
Available at: https://scholarship.law.vanderbilt.edu/vlr/vol19/iss4/6