 points to civil litigation. This goes back to the Nixon years. It's a case called Fitzgerald that says presidents can't be sued civilly when they're doing president things. So Donald Trump essentially said this has to be applied to criminal things too. If it's not, we will have a situation where forevermore presidents will be mired in a miasma of criminal prosecutions for things they do as president. Their political enemies will charge them with crimes and the presidency will become debilitated forevermore.