Throughout the Trump presidency, I’ve been struck by the extent that his defenders relied on a single word: “precedent.” Rather than engage with his conduct, they shrink back from the alleged negative implications of holding him accountable. At every stage in the various investigations (and both impeachments), we’ve been treated to a parade of arguments that go something like this:

Before the Mueller investigation: “Do we really want to set a precedent of using the FBI to investigate a presidential campaign?”

During the Michael Cohen prosecution: “Doesn’t raiding a president’s lawyer’s office set a dangerous precedent?”

During the Mueller investigation: “Are we really going to set the precedent that the president can obstruct justice by using his constitutional authority to fire his own appointees?”