Almost everyone's against the use of litmus tests in the process of nominating and confirming justices to the Supreme Court. And, on most things, that prohibition makes sense. But I'd like to propose one question that should be asked of every potential justice: When the subject of pop music comes up, do you suddenly become a total jackass?

Call it the John Roberts rule. Because, as the New York Times' Charlie Savage notes, when the current chief justice was working in the Reagan White House, he was assigned to weigh in on the subject of a proposed letter of commendation from the president to Michael Jackson, who was then at the height of his popularity. The letter was to be published in a special issue of Billboard devoted to Jackson.

Roberts, to put it mildly, was not a fan of the idea. In a memorandum, he expressed his displeasure:

I hate to sound like one of Mr. Jackson’s records, constantly repeating the same refrain, but I recommend that we not approve this letter. Sometimes people need to be reminded of the obvious: whatever its status as a cultural phenomenon, the Jackson concert tour is a massive commercial undertaking. The tour will do quite well financially by coming to Washington, and there is no need for the President to applaud such enlightened self-interest. Frankly, I find the obsequious attitude of some members of the White House staff toward Mr. Jackson’s attendants, and the fawning posture they would have the President of the United States adopt, more than a little embarrassing.

It is also important to consider the precedent that would be set by such a letter. In today’s Post there were already reports that some youngsters were turning away from Mr. Jackson in favor of a newcomer who goes by the name “Prince,” and is apparently planning a Washington concert. Will he receive a Presidential letter? How will we decide which performers do and which do not?