Some of the students’ relatives have defended the practice — saying that it worked to change students’ behavior when nothing else could — and denounced the F.D.A.’s decision.

“I just feel like I got punched in the gut when they did this,” said Louisa Goldberg, 66, whose son Andrew Goldberg, 39, lives at the center. “I’m just so sad.”

She said that her son had brain damage and epilepsy, and that he showed severe aggression as a teenager. There were violent episodes, trips to the hospital, and psychotropic medications that left him sluggish. His mother said he was placed in physical restraints for hours at a time.

“His life was torture,” she said.

Mr. Goldberg went to live at the Judge Rotenberg Educational Center at age 19 and began wearing an electric shock device. Ms. Goldberg said her son would receive two-second shocks as a sporadic part of a broader treatment plan. He has since been weaned off the device and can do things he could not do before, like go to the movies.

“This treatment works, and I will stand by it, and I will fight for it,” Ms. Goldberg said.

In a statement on Thursday, the school said that the F.D.A. had “made a decision based on politics, not facts, to deny this lifesaving, court-approved treatment.”

“J.R.C. has provided countless hours of testimony, volumes of information and made clinicians, other staff and family members of our clients, or clients themselves, available to the F.D.A. over the past several years,” it said. “In fact, after multiple requests for the federal agency to visit the only facility impacted by this rule, the F.D.A. stuck its head in the sand and refused to visit.”

The school administers the electric shocks with a device called a graduated electronic decelerator. On Thursday, a spokeswoman for the school said it had 282 clients, 55 of whom — all adults — had been approved by a court to wear the graduated electronic decelerator after all other treatments failed.