President Trump's Executive Orders and National Emergencies

Can President Trump lawfully rescind pay raises to federal workers that have already been approved by Congress for 2019 on grounds of national emergency?

His executive order on December 28^th states as much.

He will almost certainly lose this argument in federal court. Here’s why.

In 1952, during the Korean War, President Harry Truman attempted to seize American steel mills in order to avert a strike. He used an executive order to do so, citing a national emergency (steel was needed to make weapons). 

This led to the Supreme Court decision in Youngstown Sheet & Tube Co. v. Sawyer: The Court ruled that the executive order was unconstitutional. The ruling stands as a limit to presidential authority.

Justice Hugo Black wrote for the Court. He said that the President had no power to act except in those cases expressly or implicitly authorized by the Constitution or an act of Congress.

In the present matter, President Trump is acting against Congress.

There is irony in President Trump’s constant declarations of national emergencies to justify his use of executive orders: Courts don’t buy his reasoning, and are adding to the precedents that limit presidential power.