A federal judge in Texas has taken a shocking and irresponsible action: invalidating the Food and Drug Administration’s approval of mifepristone, a medication used safely by hundreds of thousands of women each year to help terminate pregnancies as part of a two-pill regimen. For what appears to be the first time, a court has invalidated an agency drug approval — an approval that was based on extensive review of scientific evidence, earned the unanimous support of outside experts and retains, after two decades, the full backing of major professional medical organizations.

The decision is so stunning that it is reasonable to ask whether courts should have any role in reviewing the F.D.A.’s scientific decision-making at all. In fact, judges do have an important job: protecting the ability of the agency to use science and expert judgment to support the health of the American people. The Texas decision is a perversion of this role and, by undermining the F.D.A., represents a threat to the safety of millions of Americans.