After voting to acquit President Donald Trump in his impeachment trial, some Republican senators seemed to channel Maine’s Susan Collins when she said, “I believe that the president has learned from this case.”

He sure has.

Trouble is, it’s a lesson of license the unrepentant president has learned, not one of contrition or even caution.

Examples abound: Rhetorical attacks against Mitt Romney; career attacks on Lt. Cols. Alexander and Yevgeny Vindman; political attacks on the state of New York and the House Democrats who pressed the impeachment case.

And now comes an institutional attack on the Justice Department in the cascading case of Roger Stone, whose crimes are often purposely obscured by Trump’s compliant congressional and media allies.

To review: Stone, a political operative with tight ties to Trump (and previously to President Richard Nixon, whose face is tattooed on Stone’s back), was convicted on all seven counts of interfering in the congressional inquiry into Trump.

The charges could have brought a prison term of 50 years. But the professional prosecutors in the Justice Department recommended seven to nine years, which was within the sentencing guidelines range.

That triggered Trump into a tweetstorm in support of Stone and in opposition to the prosecutors, judge and even jury forewoman in the case.

“This is a horrible and very unfair situation,” Trump tweeted, adding that “the real crimes were on the other side.”

Attorney General William Barr, who has often acted more like Trump’s personal attorney, backed a lighter sentence, leading four career prosecutors to resign from the case, with one leaving the Justice Department entirely.

Barr claims that that he made his call independent of Trump’s tweet. That seems unlikely given the close association between Barr and Trump, who tweeted: “Congratulations to Attorney General Bill Barr for taking charge of a case that was totally out of control and perhaps should not have even been brought.” Trump added that the prosecutors “ought to apologize” to Stone, who at one point threatened the judge presiding over his case.

While congressional Republicans were silent or supportive, Democrats rightly were not. It’s likely that Justice Department officials expressed their displeasure at being undermined, too. Which may be one reason Barr told ABC News that Trump, in effect, should stop tweeting about Justice Department issues (a plea ignored by the president within hours when he tweeted that he had a “legal right” to intervene).

Barr also said that the tweets “make it impossible for me to do my job and to assure the courts and the prosecutors and the department that we’re doing our work with integrity.”

Time (and likely leaks) will tell if Barr was sincere in his pushback against Trump, who was uncharacteristically subdued in responding.

A test will come quickly after Friday’s reports that Barr had assigned an outside prosecutor to review the case of Michael Flynn, Trump’s first national security adviser who previously agreed to a plea deal on a charge of lying to investigators.

Politically chagrined, Collins has backtracked on her initial assessment of the impeachment lesson, calling her previous comments “aspirational.”

Collins and her colleagues should themselves be aspirational and stop ceding Congress’ necessary check on the executive branch.