THE TRUMP administration on Friday tore a big hole in an important public-health law, eroding the federal requirement that health insurance plans cover contraception. The administration argued that not many women will ultimately be affected. We hope that is true.

The contraception mandate, which stemmed from the Affordable Care Act, originally offered an exemption to churches and their closely connected organizations — but not to religiously affiliated universities, charities, small businesses and other groups that wanted no involvement in providing birth control to anyone, and particularly not through the health plans they offered. Successive rounds of litigation finally pushed the objectors and the government close to a deal, in which religiously conscious groups could opt out of offering contraception coverage in their insurance plans and federal authorities would find ways to serve employees still seeking birth control. The Supreme Court last year suggested they could come to an arrangement.

But rather than hashing out a final deal, as the court suggested, the Trump administration decided that the federal government's interest in ensuring women access to birth control is not very important, and therefore surrendered to the objectors. Universities, charities and small businesses will now be able to ignore the contraception mandate without doing anything but informing their employees that they will get no birth control coverage. They could allow the government to independently arrange contraception coverage for their employees — or forbid such a workaround.

In fact, these new rules would apply to practically any private entity that does not want to provide contraception coverage, including major publicly traded companies and health insurers themselves. They would have to claim to have a religious objection, but that is not a high barrier. That is why, though the Trump administration insists that the mandate is still in force, the law has been deeply undercut.

Although it admits that it has created a huge new loophole, the Department of Health and Human Services argues that not many organizations will take advantage. Only a few relatively small groups have challenged the mandate in court. Many of the biggest organizations using the workaround the Obama administration tried to implement have no problem with it and may continue allowing federal authorities to arrange contraception coverage for their employees. And it is unlikely large, publicly traded companies will now change their benefits packages.

Even so, the administration estimates — very roughly — that tens of thousands, and perhaps more than 100,000, women will now have to pay out of pocket for their birth control or look for help elsewhere. Others predict more. The administration argues that these women should seek out unrelated federal programs that provide discounted or free contraception. But this thinking violates the underlying logic of the mandate. Throughout the dispute over the law, the Obama administration argued that women's access to an essential benefit must be seamlessly incorporated into the rest of their health plans. Creating gratuitous barriers to contraception will result in more unintended pregnancies. We doubt that is what the Trump administration wants. But that will be the consequence.