The law requires doctors who perform abortions to have admitting privileges at nearby hospitals.
U.S. District Judge Myron Thompson handed down his decision days after a federal appeals court extended a stay on a similar law in Mississippi, which would have forced the state's only clinic to close its doors. The divided court did not overturn the law, but the majority said it is unconstitutional and suggested the clinics that challenged it are likely to win.
"The evidence compellingly demonstrates that the requirement would have the striking result of closing three of Alabama's five abortion clinics, clinics which perform only early abortions, long before viability," Thompson said.
The Alabama law, signed last year by Republican Gov. Robert Bentley, was called the Women's Health and Safety Act. Supporters said it was aimed at protecting women seeking abortions.
But Planned Parenthood Southeast, which has clinics in Birmingham and Mobile, and Reproductive Health Services, operator of a clinic in Montgomery, said the law has no medical purpose. They also said the doctors who perform abortions at their facilities travel from other cities and are unable to get local admitting privileges.
"These admitting privileges were not designed to make women safer," said Susan Watson, executive director of the American Civil Liberties Union of Alabama.
Many states have recently passed laws on admitting privileges, although most are on hold because of court action. In Texas, where the state's law is being enforced, more than half the 41 clinics in the state had closed by late July, and a report found the number of second-trimester abortions had actually gone up even though the number of abortions overall was down.