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.

The lead plaintiff, the Alliance for Hippocratic Medicine, had initially challenged the FDA’s approval of mifepristone.

But the matter before the high court now is more narrow -- whether the FDA's subsequent regulatory decisions about the drug, in 2016 and 2021, were sound.

In court filings, the Alliance Defending Freedom, a Christian conservative legal advocacy representing the plaintiffs, has claimed mifepristone is not safe and that the FDA didn't study it closely enough before it was approved.

The group also argued that the FDA’s decisions in 2016, lowering the recommended dosage and extending the use from seven weeks through 10 weeks of pregnancy, and in 2021, which permanently lifted the restriction on requiring abortion pills to be dispensed in-person, were unsound.

In January 2022, the FDA went further by allowing retail pharmacies to provide the drug too, either by mail or in person, so long as they meet certain requirements, which the plaintiffs claim violate federal laws that prohibit the distribution of chemical abortion drugs by mail.

The FDA rejects the claims, arguing that mifepristone is safe when used as indicated and directed, and that the pill went through a thorough and comprehensive review before being approved.

Mifepristone is a drug typically used in combination with another drug, misoprostol, to induce an abortion or to help manage an early miscarriage.

The medication works by blocking progesterone, a hormone that the body needs to continue a pregnancy.

This causes the uterine lining to stop thickening and to break down, detaching the embryo. The second drug, misoprostol, taken 24 to 48 hours later, causes the uterus to contract and dilates the cervix, which will expel the embryo.

The FDA authorized mifepristone for medication abortion in September 2000 for up to seven weeks' gestation, which was then in 2016.

However, the World Health Organization says the two drug-regiment can be taken up until the 12-week mark of pregnancy.

Solicitor General Elizabeth Prelogar gave a brief rebuttal on behalf of the federal government, summarizing their view that respondents do not have standing and that their sought remedy of nationwide relief is not warranted.

"They have said they fear there will be emergency room doctors somewhere, someday who might be presented with some woman suffering an incredibly rare complication and the doctor may have to provide treatment, notwithstanding the conscience protections," she said.

"We don't think that harm has materialized -- but what the [lower] court did to guard against that very remote risk was issue sweeping nationwide relief that restricts access to mifepristone for every single woman in this country and that causes profound harm," she added. "It harms the agency, which had the courts come in and displace the agency's scientific judgments. It harms the pharmaceutical agency that is sounding alarm bells that this would destabilize the system for approving and regulating drugs. And it harms women who need access to medical abortions under conditions the FDA determined were safe and effective."