Justice Clarence Thomas asked Solicitor General Elizabeth Prelogar if there is anyone who would have have a legal right to sue in this case -- which quickly emerged as the first major topic of the court's questioning of the federal government. The FDA has claimed the current plaintiffs do not have standing, with Prelogar suggesting at the hearing that their relationship to people who use mifepristone is too speculative and remote.

Prelogar said there may be an instance where a "competing drug manufacturer might sue and claim that FDA approval of a drug creates a competitive harm or injury or injury in that sense."

Chief Justice John Roberts asked if there is a number of adverse events or a number of patients who go to the emergency room in which the arguments would change. Facing such questions, Prelogar responded by reiterating her view that these possibilities appeared to be too theoretical and detached from specific decision-making and the history of patients who have used mifepristone.

Pelogar, in her opening statement, contended the anti-abortion plaintiffs have no standing and defended the FDA's approval of the drug.

She warned that the relief sought by the Alliance for Hippocratic Medicine would both "severely disrupt the federal system for developing and approving drugs" and "inflict grave harm on women across the nation."

Oral arguments have begun over the abortion pill mifepristone and whether the FDA lawfully relaxed restrictions on the drug to make it easier to access to end a pregnancy.

Solicitor General Elizabeth Prelogar will be the first to give an opening statement.

With arguments set to begin shortly, there are large competing demonstrations outside the building.

Small groups of pro-abortion rights demonstrators were staging sit-ins on sidewalks and roadways.

There is a heavy police presence and Capitol Police are conducting some arrests.