Abortion pill “reversal” is the idea that the effects of the first pill in a medication abortion regimen — a drug called mifepristone — can be counteracted if someone decides not to take the second pill. Mifepristone works by blocking receptors for progesterone, a hormone needed to continue a pregnancy. Providers of “reversal” care try to override this block by flooding the zone with high doses of progesterone in the hopes of continuing the pregnancy.

The practice is not federally approved. Scientific support for the idea is spotty at best — and reports of success are undermined by the fact that, when taken alone, mifepristone can be ineffective at causing an abortion, making it unclear whether the progesterone provides any added benefit.

But no study has conclusively debunked the notion, either. At least one study has suggested there may be an added risk of severe bleeding in patients who take mifepristone without then taking the second abortion drug. In defending the law, the state cited no instances of harm or patient complaints from the practice.

The treatment is most often provided in anti-abortion clinics, many of which are faith-based.

It is unclear how often it occurs, but even using proponents’ own figures, it still happens in fewer than 0.5% of medication abortions.

And in case you were wondering:

Domenico, who previously served as solicitor general for the state of Colorado, was nominated to the federal bench in 2017 by then-President Donald Trump.