Alas, Mr. McCarthy is far from alone in debasing himself for the benefit of the former president. So on the occasion of Mr. Trump’s second not-guilty plea in three months, after he was arrested and arraigned on the charges on Tuesday in a Miami federal court, let’s take apart the two most common, and most absurd, defenses of his behavior.

Selective Prosecution. This is the “witch hunt” narrative that has animated the Republican Party for years. In this account, the “deep state” has always had it in for Mr. Trump, targeting him for things that other officials, especially Democrats, get away with. “If you’re Donald Trump, they’re going to come get you for anything,” Byron Donalds, a Florida congressman, said on CNN on Tuesday. “But if you’re Hillary Clinton or Joe Biden, they’re going to investigate very, very slowly, and let’s see where it actually ends up.” This is an upside-down way of looking at what’s happened over the past several years.

It’s true that Mr. Biden was found to have classified documents from his time as a senator and as vice president in his personal possession, too, some stored in his Delaware garage. Same with former Vice President Mike Pence. In both cases, the removal of secret material after their terms ended was apparently inadvertent, and there was no indication that either man even knew he possessed the documents. Both men cooperated with authorities, immediately returning the documents to their rightful owner, the federal government. Even so, Mr. Biden’s attorney general, Merrick Garland, quickly appointed a special counsel to look into the president’s documents case.

In contrast, it has taken the government more than a year to get the hundreds of classified documents Mr. Trump took from the White House. First the government asked politely, then it issued subpoenas, and finally it executed a search warrant. Even now, it would be foolish to assume that everything in Mr. Trump’s possession has been turned over. The indictment charges him with multiple acts of obstruction, including instructing his personal aide Walt Nauta to move boxes around in order to hide them from his own lawyers, and later suggesting to one of his lawyers that the lawyer “pluck” out any documents that might get Mr. Trump in trouble.

And what of Mrs. Clinton, against whom Mr. Trump still seems to believe he is running, seven years later? It has become an article of faith among Republicans, both the “Lock her up” crowd and the supposedly more serious ones, that Mrs. Clinton committed a major crime by using a personal email server to conduct government business while she was secretary of state. Even Chris Christie, the former New Jersey governor who plays one of the few responsible politicians in the modern G.O.P., called the allegations against her “damning.”