Ordinarily, when a doctor warns you of the risks connected to a medical procedure, you can trust that you’re being told the truth, or at least what your doctor believes to be true. For any woman seeking an abortion in South Dakota, though, this is no longer the case. Thanks to an 8th Circuit Court of Appeals ruling this week with far-reaching implications, doctors performing abortions will now be legally mandated to mislead their patients. The result is not just an attack on abortion rights that’s likely to be copied in other states—it’s an attack on the broader idea that policymaking should privilege fact over fantasy.

At issue is a 2005 law that, among other things, requires doctors to warn women that abortion would subject them to increased risk of “[d]epression and related psychological distress” and “[i]ncreased risk of suicide ideation and suicide.” This would be perfectly legitimate if it were true, but the vast preponderance of medical and academic research shows that it is not. “The best scientific evidence published indicates that among adult women who have an unplanned pregnancy, the relative risk of mental-health problems is no greater if they have a single elective first-trimester abortion than if they deliver that pregnancy,” concluded an American Psychological Association task force that studied the issue. (Italics theirs.)

To justify a law forcing doctors to tell women otherwise, the 8th Circuit has turned the burden of evidence on its head. Essentially, it said that the state doesn’t have to prove the suicide advisory is true—rather, the plaintiffs have to prove it definitively untrue. “[I]n order to render the suicide advisory unconstitutionally misleading or irrelevant, Planned Parenthood would have to show that abortion has been ruled out, to a degree of scientifically accepted certainty, as a statistically significant causal factor in post-abortion suicides,” the court concluded. In other words, Planned Parenthood would have to prove a negative.

For many observers, the idea that there’s a causal link between abortion, depression, and suicide probably makes a certain amount of sense. After all, for most women, an unwanted pregnancy is deeply distressing. There are clearly women who feel immense guilt about their abortions, particularly if they come from communities where abortion is taboo. Furthermore, there is a statistical correlation between abortion and suicide—women who’ve had abortions are more likely than women who haven’t to die by their own hands.

If you think that that makes the antiabortion movement’s case, however, consider that, according to the American Psychological Association, women who’ve had abortions are also more likely to be murdered than other women. No one, however, would argue that they are murdered because they have had abortions. Rather, the same factors that have left them vulnerable to unwanted pregnancies can leave them vulnerable to other acts of violence. “Unwanted pregnancies are not random events,” says the APA report. “The lives of women who have unwanted pregnancies or abortions differ in a variety of ways from the lives of women who do not have unwanted pregnancies or abortions, and do so before, during, and after pregnancy occurs… [S]ubstantial research literature has shown that systemic and personal characteristics that predispose women to have unintended pregnancies also predispose them to have psychological and behavioral problems.”

In arguing that abortion causes suicide, abortion opponents turn correlation into causation. Consider the work of Priscilla Coleman, an antiabortion professor at Bowling Green University who is cited repeatedly in the 8th Circuit’s opinion. In 2009, she coauthored an article in the Journal of Psychiatric Research titled “Induced Abortion and Anxiety, Mood, and Substance Use Disorders: Isolating the Effects of Abortion in the National Comorbidity Survey.” It purported to find that, adjusting for other variables, abortion was an increased risk factor for a variety of mental-health problems and substance-abuse disorders. Using the same data set, though, the researchers Julia Steinberg of the University of California, San Francisco, and Lawrence Finer of the Guttmacher Institute were unable to replicate Coleman’s results, and they soon discovered that she and her colleagues had made errors in their calculations. Acknowledging this, Coleman and her coauthors published a correction in which they offered new figures that, they argued, still proved their case.

Looking at those figures, Steinberg and Finer found even more serious problems. Coleman and her coauthors, it turned out, didn’t just rely on mental illness that manifested after abortion—they counted mental-health diagnoses across women’s entire lifetime. Thus if a depressed woman had an abortion, the abortion was treated as a risk factor for her depression, even if the depression came first. A review by the journal’s editor, Stanford’s Alan F. Schatzberg, and Harvard’s Ronald C. Kessler concurred with Steinberg and Finer’s critique. “[T]he Coleman et al. (2009) analysis does not support their assertions that abortions led to psychopathology in the … data,” they wrote.

But if Coleman’s research isn’t respected by others in her field, it nevertheless served as a justification for upholding South Dakota’s law. The 8th Circuit basically ruled that legislatures are free to pick and choose which "science" they’d prefer to believe. “We express no opinion as to whether some of the studies are more reliable than others; instead, we hold only that the state legislature, rather than a federal court, is in the best position to weigh the divergent results and come to a conclusion about the best way to protect its populace,” the court wrote.

The consequences of such reasoning go beyond abortion. The court’s ruling should also comfort creationists, anti-vaccine activists, global-warming deniers, and purveyors of ex-gay therapy—anyone who wants ideological fictions to be given the same policymaking weight as scientific consensus. For now, though, the immediate effect will be on women with unwanted pregnancies in South Dakota. They’re the only people in the United States who must, by law, be deceived by their doctors.