The Supreme Court’s recent decision in Donald Trump v. United States — in which a majority of the justices found that presidents are immune from prosecution for many actions taken during their presidency — is a legal earthquake. One way to see what a huge difference this new ruling will have is to look back at Watergate to see what behavior the Supreme Court excused for all presidents. I wrote about ex-President Trump’s ongoing criminal exposure in my new book “Corporatocracy.” I worried in that book that Trump would not be held accountable by the courts. As it turns out,...