House Majority Leader Kevin McCarthy (R-Calif.) at the White House on May 16. (Evan Vucci/AP)

The rule of law has taken some gut punches the past few days, but not from the source most widely blamed: the outlandish memo written by President Trump’s lawyers claiming that he’s above the law, followed by Trump’s “I-can-pardon-myself” tweet.  Constitutional democracy can survive self-aggrandizing claims by a president and his legal team; far more crucial is how our institutions, leaders and citizens respond to those assertions and act to constrain them. And it is on that measure that our system has been put at risk.

All presidents chafe at the legal restraints placed on them. President Bill Clinton refused to submit to a civil deposition while in office and pressed his claim all the way to the Supreme Court. President George W. Bush’s White House sent top aides to the hospital bed of the attorney general to get approval of a domestic surveillance program the Justice Department believed to be illegal. A new book reminds us that President Barack Obama put forward the view that he could launch an offensive military strike even when the United States was not in danger — even though Obama had argued the opposite while seeking the presidency.

The rule of law turns on how our legal and political systems respond to presidential overreach — and what presidents do when their excessive claims are rejected by the other branches. The Supreme Court unanimously rebuffed Clinton’s claim that he could not be deposed — and then he submitted to questioning in the Paula Jones case. Bush’s deputy attorney general, James B. Comey, refused to bend on the surveillance issue — and the president radically changed his domestic intelligence-gathering program. Congress declined to give Obama authority to bomb Syria, and the president (perhaps relieved) refrained from an attack.

Today, the greatest threat to the rule of law is not the reckless claim by Trump’s lawyers of presidential immunity, or the erratic Sunday-show ruminations of his lawyer Rudolph W. Giuliani. What is weakening our government under law is the flaccid response that key players in our system are making to Trump’s above-the-law assertions.

A few hours after the Trump memo went public — along with a tacit acknowledgment that the White House had lied about the president’s role in generating a false statement about a meeting with Russians at Trump Tower — the leading candidate to become the next speaker of the House, House Majority Leader Kevin McCarthy (R-Calif.), declined to criticize either the White House lies or the extraordinary claims by the president’s legal team. Republican strategist Steve Schmidt said this abdication of responsibility “disqualified” McCarthy to hold the office of speaker. As The Post’s Jennifer Rubin recently noted, congressional Republicans who had no trouble accusing Obama of “obstruction of justice” for a wide array of acts now take the view that a president has unlimited power to block any investigation of his choosing.

Over on the Senate side, some Republicans have finally started to talk about reining in Trump — but they seem unwilling to do much more than talk. Sen. Bob Corker (R-Tenn.) tweeted that he was working on how to “push back on the president using authorities in ways that were never intended.” Corker’s tweet followed a speech given by his Senate colleague, Jeff Flake (R-Ariz.), who accused Trump of debasing the presidency due to “only a passing familiarity with how the Constitution works.” 

But it is unclear if they will back these words with actions. Unlike most of us, Corker and Flake could actually do something immediately to curtail Trump’s flouting of the law: They could be the deciding votes on a roll call in the Senate. They could refuse to approve Trump nominees, block Trump’s appointees to the federal bench, even threaten to flip control outright to the Democrats unless Trump agrees to cooperate fully with special counsel Robert S. Mueller III’s investigation. Trump’s words are not the greatest danger to the rule of law; it is the passivity of Republican leaders in the face of those words that is the real threat.

Nor can we rely on bipartisan public support to defend the rule of law. We are increasingly divided into political tribes with group allegiances stronger than our shared commitment to common values. Our confidence in the institutions that could constrain the president — Congress, the media, the courts — is near an all-time low . Republicans approve of Trump’s performance with near-record levels of support; presidential spokespeople who should be chagrined to see Trump and impeachment mentioned in the same sentence raise the “I-word” because of its rallying effect on Trump’s supporters.

Soon — and perhaps that time has already come — Mueller will have to subpoena Trump to testify. When he does, the measure of the rule of law will not be the position Trump takes vis-a-vis that subpoena, but whether the courts order it enforced and then whether Trump complies with such a directive. Ultimately, what Trump says about the legal constraints on his power matter little; what our system does to enforce those limitations — and whether leaders in both parties side with those institutions or a president who may refuse to obey them — will be the real test.