James A. Feldman, a Washington lawyer, has argued before the Supreme Court 46 times.

Since audio recordings of last week’s health-care arguments before the Supreme Court were released, the performance of Solicitor General Donald Verrilli has been criticized. But factors such as the number of times a lawyer is interrupted or hesitates while arguing in our nation’s highest court are not a sound basis for judging the “Worst Week in Washington” — or even for guessing how the court will ultimately rule. Those who understand the challenges of Supreme Court argument — people who have argued before the court — have not criticized Verrilli’s performance. It is instructive to look closely at some rules of this particular game.

A Supreme Court argument was never intended to be a public-speaking contest in which each contestant has an equal chance to showcase his ability to deliver a polished oration. All of the justices may interrupt at any time — out of puzzlement, to test his or her tentative views of a case, or to persuade other justices of his or her view. Oral argument is the time to address the issues on the justices’ minds. The advocate does not get to ask for time to complete a thought. He or she has to break off mid-sentence to address whatever question is asked.

During the 56 minutes of Verrilli’s initial argument last Tuesday — before his four-minute rebuttal at the end — he was interrupted 103 times by the justices. Frequently, the questions came so fast that he had the chance to get out only 20 or so words before a further question and change of subject. When he had the rare opportunity to elaborate a little, his argument became much clearer and easier to listen to. By contrast, Paul Clement, who was arguing for the states that challenged the Affordable Care Act, was interrupted 33 times in a 30-minute argument. He spoke for an average of about one minute, or roughly twice as long as Verrilli, before being interrupted. The fewer interruptions could stem from numerous factors, including the personal styles of the justices who questioned Clement or their favorable initial inclinations in the case. But an advocate before the court has little control over the quantity or quality of questions from the bench.

The advocate’s primary goal in oral argument, especially in a case that is likely to be hotly contested, is to persuade not the justices who seem to favor your side but those who seem inclined against you or who are on the fence. Questions that seem to make favorable points for an advocate can be a distraction. Worse, a broad argument suggested by a justice who appears to be leaning your way can turn out to be a deterrent for those you are trying hardest to persuade.

A major argument of Verrilli’s opponents was that, while the Constitution grants Congress the power “to regulate . . . commerce,” the mandate to purchase insurance required people to create, rather than regulate, commerce. Justice Stephen Breyer asked Verrilli for comments on the thinking — which Breyer seemed to favor — that there is little constitutional distinction between regulating existing commerce and creating new commerce, and that the mandate is constitutional because Congress’s power extends to both. That is an interesting point, but elaboration is not likely to win any converts among those justices Verrilli needed to persuade, as the skeptical follow-up from Justice Anthony M. Kennedy (“Are there any limits on the Commerce Clause?”) suggested.

The only good measures of a Supreme Court advocate are whether he has made the best arguments in favor of his position and whether the justices understand those arguments. In this respect, Verrilli succeeded. In their final questions to those who opposed the government, two justices who had expressed some skepticism of Verrilli’s position demonstrated that they understood the position’s legal strength. One of Verrilli’s key arguments was that the mandate to buy health insurance is a regulation of commerce in health care because, even if an individual is not engaging in commercial health-care transactions at a given time, “the government’s position is that almost everybody is going to enter the health-care market” at some point. Chief Justice John Roberts used that terminology when questioning an attorney who was challenging the law. A few minutes later, Kennedy demonstrated that he understood a ruling in this case would not open the floodgates to federal regulation of all lines of commerce — a key point Verrilli had been urging — when he said to the same attorney: “The young person who is uninsured is uniquely, proximately very close to affecting the rates of insurance and the costs of providing medical care in a way that is not true in other industries. That’s my concern in the case.”

Those who do not know or fully understand the court’s rules and practices at oral argument should hesitate to judge the performance of those who argue there.