On Monday, in a major defeat for those who want to limit access to abortion, the U.S. Supreme Court struck down restrictions on abortion providers imposed by Texas state law. The law, passed in 2013, required that abortion clinics’ doctors have admitting privileges to local hospitals and that clinics meet the standards of “ambulatory surgical centers.” Texas argued that the requirements were necessary to protect women’s health, while the law’s challengers argued that they placed too much of a hardship on abortion providers and that the number of abortion clinics in the state could drop to about 10 from 41. The outcome is somewhat unusual. Historically, the Supreme Court’s decisions on abortion and contraceptive cases have more often leaned conservative.

In a 5-3 ruling, the court held that the Texas requirements amounted to an “undue burden.” (You can read more about how the definition of “undue burden” is a math problem in disguise elsewhere on FiveThirtyEight.) Requirements like these weren’t limited to Texas. Twenty-two other states had required abortion facilities to meet standards similar to those for ambulatory surgical centers, as of June 1, according to the Guttmacher Institute, a research organization that advocates for abortion rights. Five states had required providers to have admitting privileges.

In his dissent, Justice Clarence Thomas invoked Justice Antonin Scalia and wrote that the “decision exemplifies the Court’s troubling tendency ‘to bend the rules when any effort to limit abortion, or even to speak in opposition to abortion, is at issue.’” However, despite Thomas’s objection to the jurisprudence, liberal-leaning decisions on abortion rights haven’t been the norm over the Supreme Court’s history. In the 42 abortion- and contraceptive-related cases that the court ruled on from the 1970 through 2014 terms, the court ruled in a conservative direction in 60 percent of them (25 total), according to the Supreme Court Database, a court-tracking website maintained by a handful of academics. That trend is especially the case when the petitioner wins. In only five previous cases had the petitioner prevailed and the decision leaned liberal. (That makes the victory for Whole Woman’s Health, the petitioner in this case, even more notable.) In other words, it’s been rare to challenge a lower court’s ruling in an abortion case and secure a liberal decision by the highest court in the land.