John Dean was a key player in the previous great constitutional crisis facing the United States of America.

He served as White House counsel during the Nixon administration. He went before the Senate Watergate Committee and declared there was a “cancer growing” on the presidency. The nation got all worked up over that testimony.

Dean eventually would be convicted of crimes and would serve time in prison for his role in covering up the Watergate scandal.

So what does the House Judiciary Committee, which plans this week to open more hearings on the current crisis? It’s going to summon John Dean to testify about what he knows about Robert Mueller’s findings on Donald Trump’s presidential campaign.

That’s it! A former Watergate-related criminal is going to talk to us about an investigation into which he has next to zero personal knowledge.

Robert Mueller concluded his probe into alleged collusion between Trump’s campaign and Russians who hacked into our electoral system. He said Trump didn’t “conspire” to collude; he left the door open on matters relating to obstruction of justice.

Dean has expressed dismay at Mueller’s findings. He has emerged as a Trump critic. So, on that score I’m on his side.

Still, my questions remain: What does John Dean bring to this matter? What unique expertise does he have? What is the Judiciary Committee going to hear from Dean that it hasn’t already heard from other peanut-gallery spectators?

Here’s a thought: Forget about Dean and bring Mueller himself to Capitol Hill.