Responding to an April mandate from a federal district court that would make the emergency contraception drug Plan B available without a prescription to all women regardless of age, the Obama administration reduced current age restrictions on the pill from 17 to 15.

That political compromise, despite being the U.S.’s most progressive legislation on emergency contraception to date, continues a historical pattern of ignoring the very studies U.S. administrations have ordered to evaluate the safety of the drug and the societal effects of increased access to emergency contraception.

After a 2005 study by a team of scientists at the University of California, San Francisco, confirmed that Plan B—then a two-step regimen consisting of two 0.75-milligram pills containing the hormone levonorgestrel—was not only safe to use but had no effect on the sexual behavior of teens who had access to it, the U.S. Food and Drug Administration (FDA) commissioned the same researchers to conduct a second study, this time to evaluate whether or not young people could use Plan B responsibly. “We found that not only could they understand it, but they would make decisions about using it that were the same decisions adults would make,” says professor of obstetrics and gynecology Cynthia Harper, who led the study.

These studies were part of a docket of scientific evidence that FDA Commissioner Margaret Hamburg took into account when she issued an official stamp of approval for Plan B—for use by women of all ages—in December 2011. “There is adequate and reasonable, well-supported and science-based evidence that Plan B One-Step is safe and effective and should be approved for nonprescription use for all females of child-bearing potential,” said Hamburg, a physician.

In 2006, one year after Harper’s team published its findings, the FDA had eliminated the 1999 prescription requirement for Plan B purchases but maintained age restrictions of 18 and over on the drug. Three years later, after Israel-based Teva Pharmaceuticals released Plan B One-Step, a new and easier-to-use version of the drug that replaced the two 0.75-milligram pills with a single 1.5-milligram dose, the FDA reduced the age limit from 18 to 17. And in 2011, just days after Hamburg approved Plan B, U.S. Health and Human Services Secretary Kathleen Sebelius vetoed the decision, barring over-the-counter sales of the pill to girls younger than 17. Sebelius, who does not have a science background, objected to the FDA’s ruling on the grounds that very young girls would suffer detrimental side effects from using emergency contraception. “About 10 percent of girls are physically capable of bearing children by 11.1 years of age,” Sebelius said in December 2011. “It is common knowledge that there are significant cognitive and behavioral differences between older adolescent girls and the youngest girls of reproductive age.”

Responding to this concern and to public worries that young people might misuse or abuse emergency contraception, the FDA—along with a grant from Teva—funded a study to discover what age groups would request the contraceptive if it were made available, and whether or not they would use the pill correctly. In 2012, after tracking girls who came into health clinics for the pill in five cities, Harper—the same researcher who conducted the 2005 study—and her team of researchers found that the bulk of girls requesting access to Plan B were between 15 and 19. Of the 340 girls they tracked only one 11-and one 12-year-old came into the clinics looking for Plan B. “Age 14 is really the first age where you find any numbers of girls using contraception,” Harper observes. “Most girls younger than that are not yet sexually active and don’t seek care.”

Women’s health advocacy groups say Sebelius’s restriction on Plan B is unjustified by science. “Once [Plan B] has been deemed safe and effective, it should be available with no barriers that aren’t medically necessary,” asserts Sharon Levin, director of federal reproductive health policy at the National Women’s Law Center in Washington, D.C. Planned Parenthood Federation Director of Medical Services Deborah Nucatola said that restricting Plan B is illogical. “The bottom line is that emergency contraception is safe and effective,” she stated. “Expanding access to emergency contraception to all women makes scientific and medical sense.”