One day, law professors may use President Donald Trump’s case in an exam: Find all the evidence of obstruction of justice.

Diligent students will find a wealth of material, if news accounts are proven to be true: requesting a loyalty oath from then-FBI Director James Comey; pressuring Attorney General Jeff Sessions to remain in charge of the Russia investigation to protect Trump; leaning on Comey to let off former National Security Adviser Michael Flynn; firing Comey; cooking up a pretext for firing Comey; telling Lester Holt of NBC News that he fired Comey because of the Russia investigation; falsely suggesting there were White House tapes so as to affect Comey’s testimony; threatening some kind of legal action against Comey for “leaking”; launching spurious conspiracy theories (unmasking, accusing Barack Obama of wiretapping Trump Tower while he was president, smearing FBI officials who could be witnesses) to discredit the investigation; trying to get one of the potential FBI witnesses, Deputy Director Andrew McCabe, fired; drafting a misleading statement about Donald Trump Jr.‘s June 2016 meeting with a Russian lawyer in Trump Tower; ordering that special counsel Robert S. Mueller III be fired; and publicly denying he ever considered firing Mueller.

We’ve probably missed a few, but even a mediocre law student could get an A on that test.

The evidence of obstruction is simply overwhelming at this point. “Mueller and his team surely have evidence on obstruction of justice that has not yet been made public,” writes Jeffrey Toobin in the New Yorker. “But even on the available evidence, Trump’s position looks perilous indeed. The portrait is of a president using every resource at his disposal to shut down an investigation — of Trump himself. And now it has become clear that Trump’s own White House counsel rebelled at the president’s rationale for his actions.”

What’s more, at least two Trump advisers likely think Trump obstructed justice. Legal team spokesman Mark Corallo reportedly quit after he concluded there was obstruction of justice in drafting on Air Force One the statement about the Trump Tower Russia meeting. Second, the White House counsel very likely made a legal judgment (not simply a political one) in refusing to help Trump fire Mueller.

Bob Bauer observes on the Lawfare blog, “McGahn would have had every reason to object to the peculiar, if not wholly specious, grounds that the president apparently asserted for a firing. What counsel would have wished to advise the Justice Department that Mueller’s fatal ‘conflict’ arose out of his unwillingness to remain a member of a Trump golf facility that had raised its fees?”

In other words, once again a phony pretext was to be used to fire someone atop an investigation of the president. While not determinative as a legal matter, the conclusions by Trump’s own legal advisers would, in the minds of the public, be persuasive. (By the way, if research memos were drafted or the topic was discussed, the president does not enjoy an attorney-client privilege with McGahn, unlike with his personal lawyers. McGahn works for the people, not Trump.)

Republicans have refused so far to form a select committee on the issue. Many lawmakers have trafficked in ridiculous conspiracy theories and unsubstantiated accusations against Mueller and the FBI. They have refused to protect the special counsel legislatively from being fired. And they have completely suspended their own judgment as to whether Trump’s actions constitute an abuse of power — that is, an impeachable offense — relying on Mueller to make a legal judgment on possible criminal liability.

Republicans’ irresponsibility and willingness to participate in Trump’s schemes to bring down the investigation stun those who refuse to buy into crackpot conspiracies about a “deep state” and an FBI “secret society.” Republicans are so far hiding from scrutiny as to whether they will ever carry out their constitutional obligations.

Here, the news media can be much tougher, forcing GOP lawmakers to answer a series of questions, including:

• Do you think impeachment requires proof of a crime? (The historical record and the Nixon and Clinton impeachment precedents say the answer is no.)

• Do the firing of Comey and the attempt to fire Mueller because of Trump’s concern about the Russia investigation, in your mind, Mr./Ms. GOP lawmaker, amount to obstruction of justice?

• If President Bill Clinton’s lie under oath about his affair with Monica Lewinsky (which was not the topic that independent counsel Kenneth Starr was originally charged with investigating) was grounds for impeachment, would a Trump lie under oath regarding any aspect of the Russia investigation, including potential acts of obstruction of justice, also be grounds?

There are certainly more questions to be asked. However, as the evidence mounts, it is time for Republicans to go on the record. Quite simply, is there anything Trump could do that would justify opening a judiciary committee investigation on the possible impeachment of Trump?