The Supreme Court’s opinion setting new limits on the power of district-court judges to use one of their most potent tools — nationwide injunctions — marks the beginning of a profound shift in the way the federal courts do business.

Before, more than 1,000 judges had the power to issue nationwide orders that could stop the federal government in its tracks.

Now, those judges’ rulings can only apply to the actual plaintiffs in the case.

Friday’s opinion could affect any case, on any issue, where a federal judge makes a ruling that extends beyond the party or parties that actually brought the lawsuit. It left open the possibility that judges could still block government actions nationwide, but only in situations where there was no narrower approach available that would protect the actual plaintiffs whom the court is seeking to benefit.

Friday’s ruling will lead to a drastic reduction in the federal courts’ ability to check the White House, according to Judith Resnik, a professor at Yale Law School. Nationwide injunctions give courts “the capacity to tell the key nationwide actor, the executive branch, to behave lawfully,” she said.

District-court judges have repeatedly used nationwide injunctions to block Trump administration policies, including to halt the firing of civil servants, the defunding of foreign aid and the relocation of transgender women in federal prisons to men’s housing. Some of those injunctions have been lifted by higher courts; many, including those detailed below, remain in place, at least for now.

While some scholars trace the origins of nationwide injunctions, also known as “universal” injunctions, back to the early 20th century, their widespread use as a check on presidential power is relatively new and has been wielded against presidents of both parties.