The Judicial Branch can declare an Executive Order (a Presidential Order) unconstitutional if it is presented to the court as part of a case or controversy.
While the US Supreme Court is the final arbiter of constitutionality, even US District Courts can overturn an Executive Order, as was the case with President Obama's moratorium on deep water drilling in the Gulf. The lower court's decision may be appealed all the way to the Supreme Court, but in this instance it wasn't.
Judicial
Judicial
supreme court
supreme court
judicial
the executive branch
If the US Supreme Court declares an Executive Order (Presidential action) unconstitutional, it is checking the Executive Branch.
The Judicial Branch has the power to declare the acts unconstitutional.
It can declare acts of the president unconstitutional
it can declare laws unconstitutional.
It can declare acts of the president unconstitutional
The Judicial Branch had this power. The process in which this branch declare laws constitutional or unconstitutional is called the Judicial Review