An officious intermeddler is a person who voluntarily, and without request or pre-existing legal duty, interjects themselves into the affairs of another, and then seeks remuneration for services or reimbursement. Example: Person "A" leaves for vacation for two weeks during the summer. Person "B" mows "A"s lawn. "B" requests payment for this service. Under common law doctrine "B" is not entitled to any payment from "A" beyond whatever "A" cares to give. If B tries to coerce payment, B is an officious intermeddler.
An exception to this rule is if a doctor gives medical treatment to an unconscious victim. The transaction costs for the doctor are high so the courts usually will rule this as restitution rather than officious intermeddler.
Another exception to this rule, in certain jurisdictions, is the existence of a quasi-contract. In general, in order for a contract to exist, there must be mutual consent among all parties.[1] In the case of an officious intermeddler, this element of a contract is missing: consideration (goods or services) was provided by one party, but without the mutual consent of the receiving party. Therefore, no contract was made, and the intermeddler has no legal recourse to claim compensation. However, certain legal jurisdictions provide for an implied-by-law contract, called a quasi-contract, that exists solely for the purposes of remedying this unjust enrichment by giving a court legal means to enforce compensation. The distinction between an officious intermeddler, and a party operating under a quasi-contract, is that the recipient of the goods or services has knowingly accepted the goods or services, with the intention of benefiting from them without providing compensating.[2]