The rise of evil, page-94

My interpretation is that a potus is immune from prosecution when he is on the job.
Is there a US constitutional law that that defines the constitutional authority ?
The terms “conclusive and preclusive constitutional authority” refer to the scope of powers granted to the President under the U.S. Constitution that are beyond the reach of other branches of government. This means that when the President exercises these specific powers, neither Congress nor the courts can interfere or review these actions.