The Supreme Court refused on Monday to allow Texas to enforce restrictions that would force 10 abortion clinics to close.
The justices voted 5-4 to grant an emergency appeal from the clinics after a federal appeals court upheld new regulations and refused to keep them on hold while the clinics appealed to the Supreme Court.
The Supreme Court order will remain in effect at least until the court decides whether to hear the clinics' appeal of the lower court ruling, not before the fall.
The court's decision to block the regulations is a strong indication that the justices will hear the full appeal, which could be the biggest abortion case at the Supreme Court in nearly 25 years.
If the court steps in, the hearing and the eventual ruling would come amid the 2016 presidential campaign.
Chief Justice John Roberts and Justices Samuel Alito, Antonin Scalia and Clarence Thomas would have allowed the state to move ahead with regulations requiring abortion facilities to be constructed like surgical centers. Doctors at all clinics also would be forced to have admitting privileges at a local hospital.
The clinics said enforcing the new regulations would lead to a second major wave of clinic closures statewide in as many years. Texas had 41 abortion clinics in 2012; 19 remain.
The regulations would have left the state with no clinic west of San Antonio. Only one would have been able to operate on a limited basis in the Rio Grande Valley.
In November 2013, Justice Stephen Breyer wrote that four justices probably would want to review the constitutionality of the regulations.