Third, it stretches the muscles that Trump will have to use if he decides to pardon his aides and family members for crimes uncovered in the course of the Justice Department’s Russia investigation, all while reaffirming his sense that Republicans in Congress will let him get away with it.

Personally, I am convinced that the Arpaio pardon is one of many reasonable grounds on which Congress could initiate the impeachment process, and that even in the absence of high crimes and misdemeanors, Trump should be removed from office because he is unfit to serve. Republicans, by contrast, want you to think that while they strongly oppose Trump’s behavior, they are powerless to do anything about it. But they are not powerless, and now they must confront the questions raised by their own post-hoc objections to something Trump all but announced he would do several days in advance. If Republicans in Congress are not going to do anything to stop Trump, what will they do to contain the damage?

Arpaio was a public figure in good standing on the right for two decades, not in spite of the fact that he made life hell for prisoners and immigrants living in his jurisdiction, but because of it. Republicans stood by as Arpaio built his infamous “tent jails,” where temperatures sometimes exceeded 115 degrees. They stood by as he made a woman give birth while shackled to a bed. As the country’s demographics shifted over the years, some Republicans started treating Arpaio less like a celebrated hero and more like an embarrassing racist uncle, but by then, their lots had been cast.

Trump’s decision to pardon Arpaio, like Trump’s success in the Republican primary, is an outgrowth and an emblem of the GOP’s decision to foster the intellectual and cultural climates of Fox News across the country—concentrated in heavily gerrymandered congressional districts—to help them win elections. On its own terms, that project has been an incomparable success, but it has also been a moral abomination, forcing one of America’s two major political parties into complicity with the worst actors in the country. Conservatives finally discovered a vocal distaste for Arpaio after Trump pardoned him, but for decades they have done nothing to kick Arpaioites out of the coalition. Some Republicans may be genuinely uncomfortable with this arrangement, but nearly all of them represent parts of the country that are walled off from dissent.