How does the legislative branch check other branches?
The legislative branch makes laws, but the judicial branch can declare those laws unconstitutional. ... The President in the executive branch can veto a law, but the legislative branch can override that veto with enough votes.
Can the legislative branch pass whatever law it wants?
All legislative power in the government is vested in Congress, meaning that it is the only part of the government that can make new laws or change existing laws. Executive Branch agencies issue regulations with the full force of law, but these are only under the authority of laws enacted by Congress.