Just to point out, the transfer fee doesn't apply to the player but to their playing registration, so in theory Ben Arfa could say to Marseille "screw you guys, I'm off to join Newcastle", walk out and sign a contract at Newcastle, but it wouldn't do any good as Marseille would still hold his playing registration so Newcastle couldn't actually use him. Realistically, there's laws within the game which prevent clubs offering contracts to other club's players, but I'd imagine the registration thing (as well as some form of common sense - ie not committing to a contract for a player you can't use) has a bearing on how some of the employment law issues can be avoided.