[Coda]

I think that one's going to end up being a question of case law and circumstances. As I said, the contract is null, and it never carried legal weight in the first place. The contract wasn't signed by someone who had the legal ability to enter into the agreement. It would be a miscarriage of justice to pull up a contract signed by a 17-year-old when he's 25 and say "look, you agreed to this back then, you're not a minor anymore, it's binding on you because you never nullified it."

In my (non-lawyer) opinion, it's going to largely be determined by the history of the contract and the good-faith efforts of both parties. If the signer CONSCIOUSLY agrees to be bound by it after reaching the age of majority, then that's really what matters. The real challenge there is proving it, and in the event of a dispute (say, the signer agrees when he turns 18 and changes his mind at age 19) then the plaintiff would have to show proof that the signer had supported the agreement after turning 18 and then later backed down, while the defendant would have to argue that the contract was never binding and no formal action was ever taken. The only way to make this SOLIDLY binding is to sign a new contract at age 18.