rei interventus
rei interventus 〈拉〉(苏格兰)介入行为 合同一方当事人经另一方同意而作出的一定行为，并据此构成部分履行，即使合同原来并不完善，另一方也不得拒绝履行义务，否则构成违约。例如，若卖方允许买方占有出卖物，则其不能在事后否认该合同。它相当于英国法上的一项衡平法原则——合同部分履行原则。
REI INTERVENTUS
rei interventus
rei interventus (ree-I in-t[schwa]r-ven-t[schwa]s), n. [Latin “things intervening”] Actions or efforts by one party to a contract with the consent of the other party, so that the one party has made a partial performance and the other cannot repudiate without being in breach.