Sounds like we need to clarify the contract to define what version of bitcoin core should used. You could get into very detailed technical minutia for the contract. Not an issue imho. 

Say we do a contract and I commit to pay in bitcoin. Then bitcoin forks and I pay but you claim I didn't because we disagree on which fork is the "real" bitcoin. What would the justice say?

037447d9ca

The are used to eat steak? Lol
Idk how this is relevant. Argentina opened it up for contracta to be settled in anytbing. So forks would be allowed. People are free to choose. 