Federal regulatory officials missed a self-imposed deadline to ban a controversial device — only used in Massachusetts — that administers shocks to students with disabilities to control their behavior.

Jim McKinney, a spokesman for the U.S. Food and Drug Administration, said this week that he could not provide an updated timeline for agency action to ban the controversial apparatus it hoped to prohibit by the end of 2019. “We estimate the best we can” when setting deadlines he said, explaining the missed mark.

The Judge Rotenberg Educational Center in Canton, a privately operated, taxpayer-funded school that serves children and adults, is the only school in the country using an electric shock system to control students’ behaviors. Many of the students struggle with profound disorders that can cause severe aggressive and self-injurious behavior, like head-banging and biting.

Some family members of Rotenberg students say the shocks are the only way to keep their loved ones safe. But critics call the system torture. An FDA report found the short-term benefits of the shock device include a reduction of unhealthy behaviors, but risks involve burns to the skin, anxiety, fear and pain.

The FDA first proposed the ban in 2016. Two years later, then-FDA Commissioner Scott Gottlieb announced that the FDA planned to prohibit the devices, because they "present an unreasonable and substantial risk to public health."

Disability advocates have long striven to stop the shocks, staging protests in front of the school and outside the Indianapolis home of Health and Human Services Secretary Alex Azar.

Nancy R. Weiss, director of the National Leadership Consortium on Developmental Disabilities at the University of Delaware, said “it’s confusing” to disability advocates why the FDA hasn’t followed through.

“There is this place in Massachusetts that uses incredibly painful, fall-on-the-floor, screaming-in-agony level electric shock for students,’’ she said. “Why our government doesn’t protect these people, I don’t know.”

Rotenberg center Executive Director Glenda Crookes said through a spokeswoman that she hasn’t received an update from the FDA. Currently the center has court approval to use the shock device with 54 students, she said.

Officials from the Rotenberg center have long maintained that the shock devices are life-saving for a group of people who suffer from profound disorders. A Massachusetts court in 2018 ruled in the center’s favor, saying opponents could not prove that the treatment fails to meet an “accepted standard of care for treating individuals with intellectual and developmental disabilities.”

The Department of Justice also may be investigating the center. The federal agency announced an investigation in 2010 after 31 disability organizations wrote a letter urging federal agencies to stop the shocks. Last year, the federal department declined to provide information about the probe, explaining there was an “ongoing law enforcement proceeding.”

Shain Neumeier, a Northampton disability rights attorney, said the FDA lack of action is part of a years-long pattern. Neumeier is concerned about treatment at the center both for students who receive shocks and those who don’t.

The center has repeatedly faced allegations of abuse and neglect of its disabled residents. A 2018 investigationby the New England Center for Investigative Reporting found that during 2016, the school was cited 27 times by two state agencies for violations mostly related to abuse and neglect. That was more than any other school of its kind that year, according to state records.

Crookes at the time said she was “devasted” about any reports of abuse and that the school does everything it can to protect its residents. The school and its group homes are equipped with surveillance cameras, and Crookes said officials there report any problems to the state.

Jenifer McKim is a senior investigative reporter at the New England Center for Investigative Reporting at WGBH News.