faith forbids either party by concealing what he privately knows, to draw the other into a bargain from his ignorance of that fact, and his believing the contrary. This was an attempt by Mansfield to introduce the assumption of good faith into English law, and although it failed for the most part (as most areas of English commercial law no longer use uberrima fides), it is still used in insurance contracts. In insurance agreements, the insuree inevitably knows more about the risk involved than the insurer; without the requirement for pre-contractual "good faith," the insuree would have no reason to tell the truth, and insurance companies would be loath to make contracts. In the earlier case of , Mansfield had tried to challenge the doctrine of consideration. In English law, consideration is a vital part of the contract; without valid consideration, almost any contract is void. But, Mansfield argued in his judgment that it should only be treated as evidence of a contract, not as a vital element. Mansfield failed to make clear that he was referring only to consideration in commercial contracts, not general contracts, and as a result his judgment read that consideration was not required for any contract. His judgment has been much criticised by legal academics, and was effectively overruled by the House of Lords in Rann v Hughes [1778] 7 T. R. 350. Mansfield also enforced a previous judgement of the Court of King's Bench made in 1645, in which they allowed a special jury of merchants to sit in cases involving commercial law. He built up a special corps of these jurymen, some of whom, such as Edward Vaux, became noted experts on commercial law. "Lord Mansfield's jurymen" acted as an effective liaison between the merchants and the courts. Mansfield was personally a supporter of free trade who was heavily influenced by Roman law and ancient Roman and Greek writers such as Cicero and Xenophon. In 1783, Mansfield heard the case of , regarding the payment of an insurance claim for slaves killed when thrown overboard by the captain of a slave-ship – an event now known as the Zong massacre. Mansfield, in summing up the jury's verdict, said "The Case of Slaves was the same as if Horses had been thrown over board", and endeavoured to uphold the notion that slaves were property which could be destroyed in situations of "absolute necessity". But,