WASHINGTON (Bloomberg)—The U.S. Supreme Court refused to revive a challenge to President Barack Obama’s health care overhaul, leaving intact a ruling that said a California man and interest group filed their lawsuit prematurely.

The case marks the first time the high court has been called on to act on the health care law, which is also being challenged by 20 states in two lawsuits.

In rejecting the appeal, the justices dropped a hint that all nine of them will take part if they ultimately consider the law’s constitutionality. Two associate justices whose participation has been the subject of discussion—Elena Kagan and Clarence Thomas—both took part in today’s action.

Justice Kagan, who served as Mr. Obama’s top courtroom lawyer before he appointed her to the Supreme Court, was pressed by Republican senators considering her nomination this year to say whether she would disqualify herself from disputes over the health care law.

She said in a written response to questions that she played no role in formulating the administration’s legal defense, though the litigation was briefly mentioned at least at one meeting she attended.

Justice Thomas’s role became an issue because of the work of his wife, Virginia, a political activist whose name had appeared on a memo declaring the measure “unconstitutional.” The group she founded, Liberty Central, last month said her name had been added to the memo by mistake. Liberty Central also removed a position paper questioning the measure’s validity from its website.

State suits filed in Virginia and Florida claim the health care measure, which requires all U.S. residents to either obtain insurance or pay a penalty, exceeds Congress’s constitutional authority.

In the appeal rejected today, Steve Baldwin and the California-based Pacific Justice Institute asked the justices to take the unusual step of hearing an appeal directly from a federal trial court, bypassing the appeals court level.

The case is Baldwin vs. 10-369.