(CNN) — The Supreme Court on Friday protected access to a widely used abortion drug by freezing lower-court rulings that placed restrictions on its usage as appeals play out.

As a result, the US Food and Drug Administration’s approval of the drug mifepristone and subsequent actions that made it more easily accessible will remain in place while appeals play out — potentially for months to come.

The Friday night move is a striking victory for the Biden administration and its allies in the abortion rights community, which suffered a withering defeat at the Supreme Court last year when the conservative majority reversed the Roe v. Wade precedent that protected abortion rights nationwide.

The court’s brief, unsigned order did not explain why it granted the request by the Biden administration and a manufacturer of the drug to intervene. Justices Clarence Thomas and Samuel Alito publicly dissented.

The case is the most important abortion-related dispute to reach the high court since the justices overturned Roe v. Wade, triggering conservative states across the country to either ban or severely restrict the procedure. How the dispute over medication abortion is ultimately resolved could make it more difficult for women to obtain abortion, even in the states that still allow it.

At issue is the scope of FDA’s authority to regulate mifepristone, a drug that the medical community has deemed safe and effective. Mifepristone has been used by millions of women across the country in the more than two decades that it has been on the market.

The next step in the litigation will be a hearing in front of a New Orleans-based federal appeals court on May 17.

Alito suggests government might have ignored mifepristone ban

In his dissent, Alito said he voted to deny the request for a stay because the 5th Circuit has scheduled such an expedited hearing on the merits of the dispute.

He suggested that allowing the restrictions to remain in place would not lead to “any real harm during the presumably short period at issue.”

Alito wrote that the stay would not “remove mifepristone from the market” but would have simply restored “the circumstances that existed” from the time the drug was approved in 2000 to when the FDA passed new regulations to ease access to the pill starting in 2016.

“The Government has not dispelled legitimate doubts that it would even obey an unfavorable order in these cases, much less that it would choose to take enforcement action to which it has strong objections,” Alito wrote.

No other justice joined his dissent.

Lower court rulings that second guessed FDA’s assessments

The legal controversy began last November when a group representing doctors who oppose abortion filed suit, arguing that the FDA had not done enough to ensure the safety of the drug some two decades earlier.

US District Court Judge Matthew Kacsmaryk, a Trump appointee, issued a broad ruling on April 7 that blocked the approval of the drug, as well as changes the FDA made in subsequent years to make the drug more accessible. He, however, delayed the effective date of his ruling by seven days to give time for an appeal.

Rejecting the consensus of the medical community, Kacsmaryk raised questions about the safety of the drug, peppering his opinion with jargon that is often used by opponents of abortion. He labeled doctors who perform the procedure “abortionists” and explained that he would reject the term “fetus” in favor of the more inflammatory “unborn human.” Instead of referring to the procedure as a “medication abortion,” he insisted on calling it a “chemical abortion.”

The FDA, Kacsmaryk contended at one point, “acquiesced on its legitimate safety concerns — in violation of its statutory duty — based on plainly unsound reasoning and studies that did not support its conclusions.”

Mainstream medical associations have rebuked his assertions about the dangers of the drug, and mifepristone has been shown to be safer than common medicines like penicillin and Viagra.

On a key threshold issue, the judge insisted that the plaintiffs — doctors who do not use or prescribe the drug — had the legal right to be in court to make their case because they allege that the use of the drug could “overwhelm” the medical system.

Stunned by the breadth of the decision, the Biden administration and Danco, a manufacturer of the drug, filed an appeal with the 5th US Circuit Court of Appeals.

The appeals court ultimately let stand the government’s approval of the drug, but agreed with Kacsmaryk that access could be limited.

A divided three-judge panel ordered a return to the stricter, pre-2016 FDA regime around the drug, which prevents mailing the pill to patients who obtained it through telehealth, or virtual visits with their providers, rather than traveling to a clinic or hospital to obtain the drug in person. It also effectively revokes the 2019 approval of the generic version of the drug. The restrictions also affect the instructions on the label for the medication, shortening the window of obtaining the pill to seven weeks into pregnancy as opposed to 10.

It’s possible however that even with the ruling in effect, some providers could go “off-label” and continue to prescribe mifepristone up until 10 weeks.

The 5th Circuit claimed that the FDA’s rules for the drug created “an exceedingly unusual regime,” and that the anti-abortion doctors had the right to sue over it because they would “necessarily be injured by the consequences” of the FDA’s decision “to cut out doctors from the prescription and administration of mifepristone.”

The appeals court said that the statute of limitations likely barred the plaintiffs from challenging the 2000 approval, but that they were likely to succeed in their claims against the FDA’s more recent moves to adjust the rules around the drug.

The court accused the FDA of having an “ostrich’s-head-in-the-sand approach” to the drug that was “deeply troubling.”

President Joe Biden last week decried how those lower courts had handled the case.

“I think it’s outrageous what the court has done, relative to concluding that they’re going to overrule the FDA on whether something is safe or not,” he said. “I think it’s out of their domain.”

Pleas for the Supreme Court to intervene

The Biden administration asked the Supreme Court to intervene last week, with court filings from Solicitor General Elizabeth Prelogar citing “unprecedented lower court orders countermanding FDA’s scientific judgment and unleashing regulatory chaos by suspending the existing FDA-approved conditions of use for mifepristone.”

Implementing the changes to mifepristone’s rules ordered by the lower courts would “deny women lawful access to a drug FDA deemed a safe and effective alternative to invasive surgical abortion,” while putting the FDA and the entities they regulate “in an impossible position.”

Danco Laboratories, a manufacturer of the brand-name version of the drug that had intervened in the case to defend FDA’s approval of mifepristone, also requested the high court to step in.

Leaving the lower court rulings in place, the company’s attorney said in filings, would “irreparably harm Danco, which will be unable to both conduct its business nationwide and comply with its legal obligations.”

“The lack of emergency relief from this Court will also harm women, the healthcare system, the pharmaceutical industry, States’ sovereignty interests, and the separation-of-powers,” the attorney, Jessica L. Ellsworth, told the justices.

The anti-abortion doctors who had brought the case meanwhile told the justices that the restrictions the appeals court placed on the drug were “reasonable.”

“The lower courts’ meticulous decisions do not second-guess the agency’s scientific determinations; they merely require the agency to follow the law,” the challengers argued.

This story has been updated with additional details.