A new lawsuit has alleged that school officials in Kentucky improperly restrained students, causing them physical and emotional pain.
The American Civil Liberties Union (ACLU) filed the lawsuit on behalf of the parents of two children were handcuffed by the "school resource officer".
A video shows a boy with his arms handcuffed above his elbows.
The 52lb (24 kg) child is kept in restraints for 15 minutes.
The video - filmed in November 2014 - shows the handcuffs placed around the eight-year-old boy's biceps. His wrists are too small to fit inside the handcuffs.
"You don't get to swing at me like that," security officer Kevin Sumner, who is also a local deputy sheriff, tells the detained boy who cries throughout the video.
"You can do what we've asked you to, or you can suffer the consequences," he scolds, as the boy complains of pain.
The ACLU claims that the boy in the video, as well as a nine-year-old girl who was also handcuffed by Mr Sumner, have been diagnosed with attention deficit hyperactivity disorder (ADHD).
They allege that the Kenton County Sheriff's Office violated the Americans with Disabilities Act based on its treatment of the children.
Kentucky laws ban school officials from physically restraining children that are known to have disabilities.
Disabled children make up 12% of students in public schools, but they account for 75% of the students who are physically restrained by adults, according to the US Department of Education.
"Shackling children is not okay. It is traumatising, and in this case it is also illegal,'' Susan Mizner, disability counsel for the ACLU said in a news release.
"These disciplinary practices also feed into the 'school-to-prison pipeline,' where children are funnelled out of public schools and into the criminal justice system," the ACLU's statement says.
A lawyer for the deputy sheriff told the Associated Press that Sumner placed the children in restraints because "they were placing themselves and other people in danger of harm, and that's what the book says to do".