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, new information was introduced in the case, and he ruled against the owners of the ship. In doing this, he achieved his aim of preventing maritime insurance law from becoming more complicated.