What did Donald Trump do today?

He sent Rudy Giuliani out to accuse Robert Mueller of being a federal prosecutor.

Trump himself did nothing more job-related today than getting off a plane, after his brief but apparently very taxing trip to Argentina. Not only was his public schedule empty—even of golf—he also stayed off Twitter, except for a generic "Happy Hanukkah" tweet that was almost certainly written by a staffer.

But Trump's surrogate and "TV lawyer" Rudy Giuliani was dispatched to continue Trump's attack on Robert Mueller, in which Trump is an unindicted co-conspirator. Giuliani seemed to be trying to advance Trump's argument that Mueller was somehow abusing his authority by charging Trump associates with crimes when they lied to the FBI or, in Michael Cohen's case, Congress. 

Giuliani told a radio interviewer this morning that Mueller's team "obviously exerted a lot of pressure on him. Mr. Cohen unfortunately has a history of significant lies in the past."

Giuliani isn't wrong about Cohen's "history of significant lies": Cohen's role as Trump's "fixer" seems to have involved all manner of illegal and deceptive behavior, some of which he was already being prosecuted for. But as Giuliani—who made his name prosecuting organized crime using exactly the same techniques—presumably knows, it is not unethical for a prosecutor to bring charges when a known criminal lies under oath in an attempt to derail an investigation.

In getting his story straight with Trump's official line—that Cohen is lying if and only if he's implicating Trump in a crime—Giuliani is abandoning his initial version of events, which had Trump and Cohen largely agreeing about the timeline of events relating to Trump's attempt to build Trump Tower Moscow. 

So what?

• As a wise woman once said, "When you're attacking FBI agents because you're under criminal investigation, you're losing."

• It's okay to prosecute people for lying to Congress, because it's illegal to lie to Congress.

• People who are innocent of crimes don't generally have to change their stories about why they're innocent.