A federal judge last week ordered the US Food and Drug Administration (FDA) to make the emergency contraceptive Plan B One-Step (levonorgestrel) available over-the-counter to all women and girls, irrespective of age. The ruling is a welcome one, and the administration of President Barack Obama would be wise to end its history of political interference in a scientific issue by declining to appeal the decision.

FDA officials have restricted access to the ‘morning after’ pill ever since the administration of George W. Bush, despite the consistent opinions of their scientists and advisers, who have been recommending universal over-the-counter access since 2003. The drug, a hormone used in many birth-control pills, has been widely shown to be safe and efficacious, and young teens have proven at least as adept as older women in following instructions for taking it. Nonetheless, the FDA continued to require girls younger than 17 to get a doctor’s prescription, and women older than that to follow a burdensome proof-of-age procedure.

The drug regulator’s reticence can be traced to pressure from conservatives, who argued — despite studies showing otherwise — that making Plan B easier to access would encourage promiscuity and sexual risk-taking in young teens. Abortion politics also had a role: although the pill is thought to act by preventing or delaying ovulation, it might also prevent implantation of a fertilized zygote.

In 2001, women’s and reproductive-rights advocates petitioned the agency to remove the age restriction, without success. Their hope surged when a newly elected Obama publicly committed to letting agency scientists do their jobs, “listening to what they tell us, even when it’s inconvenient — especially when it’s inconvenient” (see Nature 480, 413; 2011). Then, in December 2011, as FDA head Margaret Hamburg prepared to make the drug available without a prescription to girls younger than 17, her boss overruled her. In her unprecedented action, Kathleen Sebelius, the US secretary of health and human services, speciously noted that 10% of 11-year-old girls are capable of conceiving and implied that young girls could therefore be harmed by the drug. In fact, the only documented adverse effects are nausea and delayed menses, and an 11-year-old can buy a lethal dose of paracetamol for considerably less money and with no restrictions. All the same, Obama backed up Sebelius.

Now, Edward Korman, a senior judge in the eastern district of New York, has called Sebelius’s action, which was taken less than a year before a closely contested presidential election, “politically motivated, scientifically unjustified, and contrary to agency precedent”. In a scathing decision in a lawsuit against the FDA brought by women and reproductive-rights groups, Korman noted that Plan B One-Step would be one of the safest over-the-counter drugs. He added that the administration’s position “is not about the potential misuse of Plan B by 11-year-olds … [but] an excuse to deprive the overwhelming majority of women of their right to obtain contraceptives without unjustified and burdensome restrictions”.

Those restrictions are particularly intrusive because time is of the essence in using the drug: the sooner after intercourse that the tablet is taken, the more likely it is to prevent pregnancy. The need to find an open pharmacy and show proof of age is not trivial, especially for poorer, younger and less-educated women — never mind asking those under 17 to get a doctor’s prescription.

The judge’s pointed ruling has given the Obama administration another chance to live up to the president’s promise to respect agency scientists’ findings “especially when it’s inconvenient”. But if the Department of Justice appeals, and prevails, then the ramifications will extend well beyond the fate of an emergency contraceptive. It will set a troubling precedent for political interference in drug-approval decisions.