The London Metal Exchange’s successful defence of a lawsuit over cancelled nickel trades has sent clearing members scrambling to take another look at exchange and clearing house rule books. The judgement in favour of the LME rested heavily on its power to tear up trades that was contained in the rules published by the exchange.

A head of clearing at a European bank says members are “double-clicking into rule books, looking for things that we thought were there just for catch-alls that would never