The Supreme Court followed up on the oral arguments by asking the lawyers for Kennedy and Braidwood to discuss the statutory relationship between the HHS secretary and the task force members.

"The parties are directed to file supplemental letter briefs addressing the following question: Whether Congress has 'by law' vested the secretary of the Department of Health and Human Services with the authority to appoint members of the United States Preventive Services Task Force," according to a Supreme Court order posted Friday.

Related: Supreme Court may back Affordable Care Act preventive services selection task force

The briefs are due at 2 p.m. May 5.

What it means: The order suggests that the outcome of the Braidwood case will have more effect on all kinds of federal advisory panels than on employers' preventive services benefits.

The backdrop: The Affordable Care Act requires providers of major medical insurance, including self-funded employer health plans, to cover the ACA preventive services benefits package without imposing deductibles, co-payments or other out-of-pocket costs on the patients.

The ACA calls for one panel to pick the vaccines that go into the package, a second panel to pick the women's health benefits that go into the package, and the U.S. Preventive Services Task Force to pick the remaining items in the package.

The task force is an arm of the U.S. Department of Health and Human Services.

ACA drafters tried to insulate the task force members from political pressure by having the members be unpaid volunteers appointed by the HHS Agency for Healthcare Research and Quality. The agency was supposed to pay the volunteers' task force-related expenses.

The U.S. Constitution appointments clause: The appointments clause says officers of the government should be appointed by the president and confirmed by the Senate. The Supreme Court later ruled that officers confirmed by the Senate can appoint "inferior officers."

Congress originally let cabinet secretaries appoint administrative law judges without requiring that the administrative law judges be appointed by the president or confirmed by the Senate.

In 2018, the Supreme Court eliminated that strategy by ruling on Lucia v. the U.S. Securities and Exchange Commission that administrative law judges had to be confirmed by the Senate.

Braidwood Management, the employer fighting the ACA preventive services coverage mandates, says the design of the U.S. Preventive Services Task Force violates the U.S. Constitution appointments clause because the task force members are supposed to be independent but have not been appointed by the president or confirmed by the Senate.

If the task force members are federal officers who are free to make their own decisions, they should be appointed by the president and confirmed by the Senate, according to Braidwood.

If the task force members are inferior officers, and need not be confirmed by the Senate, then the HHS secretary should be able to hire them, fire them and choose whether to accept their recommendations, Braidwood says.

Kennedy, the HHS secretary, says the task force does comply with the appointments clause because he does have the authority to hire and fire the task force members and to ignore the task force members' recommendations.

At the oral arguments last week, the Supreme Court justices and the parties' lawyers talked only about the appointments clause and how the task force members are selected and governed, not about health insurance benefits.

The Braidwood ruling could end up applying the kind of reasoning used in the Lucia ruling to the selection process for federal advisory panel members.

The possible impact: Some observers predict that typical employer plans will keep coverage in place for most of the services now in the ACA preventive services package regardless of how the Supreme Court rules.

Employers could keep those benefits in place partly because they want patients to catch problems early and partly because they believe solid preventive services hold down plans' overall costs.

But, if the Supreme Court saves the ACA preventive services package by declaring that the U.S. Preventive Services Task Force clearly operates under Kennedy's authority, that could affect federal regulations or federal policies that were shaped by other advisory panels with members who were not confirmed by the Senate, such as environmental advisory panels or labor law advisory panels.