Such contract is only possible if there is consequences to breaching the terms of piracy. C&P is still a bit simplistic and until pointless and unlawful killing is properly punished, there is really little need beyond roleplaying and that annoying "I like to cripple myself" excuse for not using some game-play options for avoiding the killing a human (or otherwise) opponent.
Turned on its head, this is a game and people playing outlaw and scoundrels should also have game-play options. However, they should be restrictive and potentially end up in a dead end (breaking rocks on foot on a prison planet comes to mind, when Odyssey hits the fan) if not done with skill.
As it is, it is practically impossible to "lose" the game. So no risk and all reward. This is reflected in the overly simplistic "do right and live - do wrong and 'die'" ruleset we have at the moment.
S
So this sort of change could then make it a bit more unwanted to actually kill you pirate target... as you now would gain notoriety....expecially if play in open.