A federal court MIGHT make that determination, should a case properly raising the question come before it. They don't automatically rule on everything the president does, though.
The judicial branch is the main actor that decides whether or not an action of the government is unconstitutional. However, technically the President can decide not to enforce parts of a law Congress passes on the basis of unconstitutionality through constitutional signing statements.
Supreme Court
Determining whether the policy is constitutional
President Thomas Jefferson questioned the constitutional right to purchase the Louisiana Territory.
The president doesn't have the job to "take action " to solve problems. It is up to congress to make laws. He can put pressure on law makers, but he doesn't have the power to make law. Much of what Trump is trying to do with laws today is not constitutional and has gone to the federal courts because of it. A president is not a king and can't make laws.
formulating the initial idea for the policy
The federal courts have been called "the guardians of the Consistution" because they judge whether laws and action conform to constitutional principles. However, a court may address a legal issue only if a relevant case comes before it. It cannot try to solve legal problems on its own.
the fact that there are niggars in the us..... jk jk;) naw but it is EXCECUTIVE PRIVALEGE
he promised federal funding for school desegregation
the electoral college casting ballots
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President Kennedy pushed for the Civil Rights Act in Congress, and promised federal funding for school desegregation.