Democratic presidential candidate Hillary Clinton. (Aaron P. Bernstein/Reuters)

PRESUMPTIVE REPUBLICAN presidential nominee Donald Trump still has not released his tax returns, breaking with decades of tradition, but he has offered the country a list of judges he would consider naming to fill Antonin Scalia’s Supreme Court seat, many taken on the conservative Heritage Foundation’s recommendation. The list is an attempt to shore up conservative support, and plenty of Republicans seem pathetically willing to be persuaded, though of course there is no reason to believe Mr. Trump would stick to the list. No matter how transparent the gesture, though, the list is another way in which Mr. Trump is damaging the country’s institutional fabric, in this case by further politicizing the judiciary.

Sadly, Mr. Trump is not alone in wreaking such damage this year. Before Mr. Trump released his list, on the Democratic side Sen. Bernie Sanders (I-Vt.) said that if he won the presidency, he would ask President Obama to withdraw Judge Merrick Garland from consideration for the court so that Mr. Sanders could nominate someone who has publicly committed to overturning the Citizens United ruling on campaign finance. Former secretary of state Hillary Clinton promised that she would have “a bunch of litmus tests” for her judicial nominees, including on Roe v. Wade, same-sex marriage, the Voting Rights Act and, yes, Citizens United, too.

Committing to a list of judicial nominees at this point and promising to apply judicial litmus tests put the country on a dangerous path.

By releasing his list, Mr. Trump has practically guaranteed that none of the judges he offered will be seen as fair over the next several months, their every ruling scrutinized for evidence that they are applying for the job — even if they try to conduct their duties evenhandedly.

Litmus tests, meanwhile, subvert the independence of the judiciary. If judicial litmus tests become acceptable, the number of commitments each side demands of its nominees would surely proliferate, the freedom of judges to decide specific cases would erode, and any assurance that those before the court could get a fair hearing would vanish.

The judiciary is different from the other two, more political, branches of government, and politicians, in their search for short-term victories, should not be so eager to erode that difference. Judges are not immune to ambition or political ideology, but Americans have long expected and should still expect that judges be guided by other values: careful thinking, reverence for the facts of specific cases, respect for the intent of the elected leaders who write the laws, openness to counterarguments, a healthy amount of modesty and allegiance to the notion that their rulings must bear a rational relationship to the laws they interpret and the precedents they have set. A world in which judges must at the very least address these expectations is far better than a world in which they are assumed to be wholly political actors who need offer no justification beyond, “I promised to rule this way.”