NASHVILLE, Tenn. — When a 5-year-old autistic boy came home from his Nashville public school with bruises and a bite mark, his parents sent him back with a recording device.

It captured a therapist slamming their son’s head on his desk, and a teacher using a martial arts technique that made him whimper and cry.

Now these and other parents are suing over their children’s treatment, hoping a federal judge will order the state of Tennessee to hold school districts accountable for complying with disability laws.

Nearly 40 years after federal laws began requiring schools to educate disabled students alongside their non-disabled peers as much as possible, many of these children are still channeled into separate and unequal educational programs, often because of serious behavioral challenges that come along with their disabilities.

Without enough training and resources to manage these behaviors, some teachers and their aides routinely isolate and restrain children — techniques that are supposed to be reserved for emergencies and last resorts — in ways that can become violent.

The U.S. Government Accountability Office found hundreds of allegations of abuse and even deaths associated with the use of restraints and seclusion in the nation’s public and private schools over two decades before 2009. Seven years later, Congress has yet to approve comprehensive legislation to limit these practices, which are disproportionately used on disabled children.

The National Disability Rights Network has done its own investigations and found little change. Students are continuing to be confined, tied up, pinned down, battered and nearly killed on a regular basis,” the nonprofit said in a 2012 report.

Jennifer, the mother of the 5-year-old, said they grew concerned as their son’s behavior changed from excited to anxious. His autism limits his speaking ability, but he managed to say “I’ll die. No school,” she told The Associated Press. She spoke on the condition their last name not be used, to protect her son’s identity.

She decided to sew an extra pocket into his clothes to hide the recording device. The results stunned her. She said she had to stop listening after hearing the abuse. Their three days of recordings are now evidence in federal court.

The city of Nashville settled with the family, but the Tennessee Education Department hasn’t conceded.

Its spokeswoman, Sara Gast, said she can’t comment on the issues being litigated. She asserted in an email that the department “is absolutely committed to serving all children and ensuring that every student has a safe and nurturing school environment.”

The state’s lawyers, however, have argued in court that it cannot be held responsible for the actions of local school districts.

A senior staff attorney with the National Disability Rights Network says this is not true.

The states are supposed to act as the “special education police,” Ron Hager said. While they can’t be aware of every single case of abuse at in a local district, they should be looking at their data to spot red flags.

“If they see high use of restraints and seclusions, high segregations, low academic performance, they should be saying, ‘This is not good. You’ve got to fix it.'”

The federal government, in turn, is supposed to be overseeing the states through the U.S. Education Department’s Office of Special Education Programs. But while the department has the power to sue to force compliance with federal disability education law, Hager said it has never done so.

After the Houston Chronicle reported this month that Texas arbitrarily set a benchmark of providing no more than 8.5 percent of students with special education, possibly depriving about 250,000 children of needed services, the Education Department said it’s investigating.

And the U.S. Justice Department — not on behalf of the Education Department — is suing Georgia, alleging that the state segregates disabled students into programs where they are isolated and receive substandard educations. A Justice Department statement says it’s the first federal challenge to a state-run school system over segregating students with disabilities.

Three of the families in Tennessee are challenging the same issue, accusing schools in the Knoxville area of segregating their children into classrooms where the students’ only common bond was their disability, not their age, grade or academic ability.

This lawsuit blames Tennessee’s funding formula, saying the state gives districts more money separate classrooms than for keeping such students in regular classrooms with supportive services. Knox County counters that it places children based on individual needs, without any consideration given to funding.

Another case in Knox County claims two 10-year-old students with autism were subjected to numerous isolations and restraints, including a “five points” pinning of their arms, legs and head. Knox says in court papers that the children were disciplined appropriately and have not been harmed.

By law, restraints and isolations are permitted in emergency situations, such as when a child begins throwing chairs or runs out of the school into the street. But after the emergency is over, school officials are supposed to figure out what is causing the problem behavior and find other ways of preventing it.

“The hope of the law has not really been implemented. Schools are still doing the same old, same old,” Hager said. “We should be so far past this right now.”