Congress (house of reps and senate)
the Supreme court
There are lots of other things involved:
All appropriations bills (spending) must originate in the house/reps
Pres is not supposed to legislate (exec orders were NOT part of the founders plan)
Supreme court (SCOTUS) reviews laws and determines if they are in line with the INTENT of the founders view of govt.
Now read that last sentence again: SCOTUS is charged with determining if a law enacted by any other branch of govt lines up with the INTENTIONS the founding fathers laid down. Note this is NOT a floating or growing interpretation, this is what the founders intended.
This last thought is where we get in trouble in the USA... some folks would just pass legislation willy-nilly for this or that reason... while others would carefully be SURE the legislation lines up with the intentions of the founders BEFORE passing it. Care to guess which group is libs and which one is conservs...
BTW: The reason I called you out was noted in a different post: Most countries accept over-bearing countries... the USA is unique in modern history as a bastion of FREEDOM... something it appears to me not many understand fully.