When the Supreme Court declares a law that was created by Congress unconstitutional, it is an example of presidential veto. popular sovereignty. checks and balances. habeas corpus.

This is not a presidential veto - a presidential veto is when the presidents vetoes a bill.

It's part of the separation of powers and of checks and balances - this is the correct answer - which means that one branch of the government (here the Court) can check on the other branches (here the Congress)