the congress can veto a law the president passed
checks and balances
The powers of the President are limited by Congress through the Checks and Balances system. Congress approves the President's appointments, and can override a presidential veto.
Separation of powers and the system of checks and balances
Checks and balances between Congress and the president are intended to limit the potential powers of both.
The president
The president doesn't have legislative powers congress does. That is their job. The president can veto a bill, sign it, or do a pocket veto.
To declare war, the President is supposed to get permission from Congress. But the President can order a "police action" that is equivalent to a war, without permission from Congress. This kills one of the "checks" Congress has over him.
This deals with the system of Checks & Balances. The President can "check the authority of Congress" by rejecting a unconstitutional law proposed by Congress. this process is called veto.The President checks Congress when he vetoes a bill that the Congress has passed. Congress can check him if a 2/3 majority votes to override his veto.Also, the President can check Congress by using the media (the "bully pulpit") to set the agenda for Congress. Presidents also tend to have success with Congress proportional to their approval rating with the public. Thus, if a president has a high approval rating, it is likely that Congress will be willing to help him accomplish his goals.
The President checks Congress when he vetoes a bill
What power does congress have over a president?
enumerated powers , in pliec powers and commerce cluse , checks and balences
The Supreme Court can declare a law passed by Congress to be unconstitutional and therefore null and void. The President can veto laws by Congress and fail to enforce them if his party has an impeachment-proof minority in Senate.