The gavel falls, and another executive order hits the skids. Federal judges, cloaked in black robes and armed with injunctions, have become the bane of President Donald Trump’s second term, much like they were for President Franklin D. Roosevelt nearly a century ago.  But Trump is involved in an important fight over the legitimate powers of the federal judiciary and his own under Article II of the Constitution. The outcome will have major implications for the constitutional separation of powers that go far beyond whether Trump is able to implement his preferred policies. Since Trump returned to the White House in January, his agenda — slashing federal agencies, curbing immigration, and empowering the Department of Government Efficiency under Elon Musk — has collided head-on with the federal judiciary. The clashes began almost immediately. On Feb....