The scenario you describe has never been the case and is already settled law. The president has largely been already held to be immune from litigation for their official acts while president. In fact, it was a huge debate because Clinton got sued civilly by Republican activists for various reasons and SCOTUS held that the trial could proceed while he was president. So in fact, the only time a president has been sued and had to participate while President was when the Republicans tried to jam up a Democratic one, in the middle of a war (Kosovo although some will claim that Clinton “started” that war precisely because of the lawsuit).
What’s specifically new here is the claim by SCOTUS that the President also has post-presidency immunity. It used to be you could use it as a defense whereby you provide evidence that you weren’t acting corruptly within your official acts. Now it’s a blanket immunity - a trial can’t even be brought and your motivations are largely irrelevant and immune from examination.
US v Nixon very clearly put limits of what the president could do in office. Under this ruling, Nixon could have kept the tapes of him ordering the Watergate break in a secret and would have remained in office.
> While the Court acknowledged that the principle of executive privilege did exist, the Court would also directly reject President Nixon's claim to an "absolute, unqualified Presidential privilege of immunity from judicial process under all circumstances."
This ruling directly contradicts and overturns US v Nixon which is a blaring signal considering just how criminally we now know Nixon, his administration, and his reelection committee was behaving.
