I would be very careful here. In John, where Jesus wrote on the ground, when the crowd was going to stone to death the adulteress, was the re-writing of the law.
When Jesus said he hadn't come to change the law, he was obviously talking about the essential spiritual components, such as the Ten Commandments, rather than the non-spiritual components, such as stoning sinners e to death.
Keeping the commandments is an aid to happiness. Stoning people is not.
