On Monday, the United States Supreme Court did something it had not done for nearly a decade: It denied a motion by the solicitor general to participate in oral argument in a case to which the federal government is not a party. It shouldn’t wait 10 years to do so again.

Argument time at the Supreme Court is one of the scarcest resources in the American legal system. It’s the only time that litigants can be certain that the justices hear their perspectives. An outside group that’s not a party to the lawsuit must seek permission to argue as an amicus, or friend of the court. In theory, anyone can receive approval. In practice, as we have documented, this privilege is granted almost exclusively to the solicitor general—who is appointed by the president and represents the federal government at the Supreme Court. In the 2010 through 2019 terms, the justices granted 307 requests from the solicitor general and only 14 from anyone else.

This favoritism toward the president’s advocate erodes the Supreme Court’s independence. The solicitor general’s opinion is widely respected, so much so that he is often called the “Tenth Justice.” By statute, the solicitor general must represent the “interest of the United States.” But that interest isn’t defined anywhere. As a result, the solicitor general can lend his credibility—and the efforts of the lawyers in his office—to the side of his choosing. The problem arises when the solicitor general uses this power to weigh in on cases that advance the president’s political agenda but have little connection to the interests of the federal government.

Take the case from Monday’s denial, two consolidated lawsuits that pit a corporation against consumer interests. In one, Adam Bandemer, a Minnesota resident, was riding in the passenger seat of a car manufactured by Ford. When it crashed, the airbag failed to deploy, leaving him with a severe brain injury. He tried to sue Ford in Minnesota—where he lived, where the airbag failure occurred, and where the car was purchased.

Ford insists that because the car was purchased used, the case couldn’t be heard in Minnesota—even though Ford sells cars in Minnesota. Instead, Ford argues, it must be fought in courts potentially hundreds of miles away in North Dakota, where the car was sold to its first owner; Michigan, where it was designed; or Canada, where it was built. (The other case had similar facts but was filed in Montana.) If the Supreme Court decides in Ford’s favor, consumers could have to travel across the country to vindicate their rights in court, likely resulting in fewer claims.

What does that have to do with the “interest of the United States?” In his brief to the Supreme Court, Solicitor General Noel Francisco offered a confusing explanation for why he should be allowed to argue before the Supreme Court in favor of Ford’s position. First, he wrote that the United States seeks to ensure that plaintiffs “have access to efficient forums” to sue corporations—a position that would seem to place the government on the side of protecting consumers’ interests. But in the next sentence, he noted an interest in protecting against “risks to interstate and foreign commerce posed by state courts’ unduly expansive assertions of jurisdiction,” and that the government defends federal officials in court. Francisco’s claim appears to be that because federal officials sometimes get sued in federal courts—which often face similar personal jurisdictional restrictions as corresponding state courts—the federal government has an interest in limiting the jurisdiction of state courts over corporations. But the federal government is protected under very different rules around possible liability and immunity than a corporation—such as the one at the center of this case—is.

The Supreme Court seemed to recognize the federal government’s interest here was not as great as Francisco claimed and rejected his bid for argument time. For roughly the last decade, though, the justices have permitted the solicitor general to weigh in on any case he wants. And solicitors general have employed that discretion to opine on many issues in cases that involved interests of states more than of the federal government, like certain abortion, affirmative action, and free speech in public schools cases.

Our research reveals that the Supreme Court’s willingness to listen to the solicitor general in virtually any case is a modern phenomenon. In the early 1900s, the solicitor general requested amicus oral argument almost exclusively to defend federal statutes or actions by federal agencies. And the court let him speak.

But, over time, the solicitor general increasingly entered political cases with little relevance to the federal government. During the 1970s and 1980s, the justices became skeptical about the reasons solicitors general were offering to request argument time as amicus, intimating that sometimes they expressed a political or policy preference as much as a legal view. During that period, the Supreme Court denied almost one-fifth of amicus oral argument motions from the solicitor general, and justices criticized those requests in private memoranda.

It’s too soon to tell whether Monday’s denial is the beginning of a trend. But those who care about the Supreme Court’s independence should hope that it is the first of many.