Like what kind of laws are you saying would act against legal contracts??
The whole point is to use the correct terms that will make them actual legal contracts to begin with!
:-/
I'm not a lawyer but in order to form binding legal contracts a lot of paperwork in written form has to be done. Written form can be paper or a mail. I find it hard to imagine right now that a smart contract will be accepted as written form in court. At least not now, maybe in five to ten years.
When you click "accept" on any software agreement, you've entered a legal (smart) contract in digital form, that is completely upheld in any court.
Even digital signatures have crossed this threshold already, and various loose forms of ID, like email or IP address (to prove in a court of law that you performed some action, for example).
We're already way beyond what you seem to claim is 5-10 years away.