quantum valebant
/ˌkwɒntəm vaˈleɪbant/Law. Now chiefly US
noun
(An action to recover) the reasonable value of goods which have been provided or delivered without a legally enforceable contract stipulating a price.
adjective
Of or designating (an action to recover) the reasonable value of goods.
Origin
Early 18th century. From post-classical Latin quantum valebant as much as they were worth (apparently not attested in Latin context) from classical Latin quantum which amount + valēbant, 3rd plural imperfect indicative of valēre to be worth.