SALEM — Disability Rights Oregon and four other groups filed a class-action lawsuit Tuesday against the state of Oregon in U.S. District Court saying the state denies hundreds of children with disabilities the right to attend a full day of school.

The lawsuit filed in federal court in Eugene comes on the first day of Oregon’s legislative session and names Gov. Kate Brown, the Oregon Department of Education and its director, Colt Gill, as defendants.

It says that children with disabilities are frequently removed from the general classroom and given instruction separately or are sent home because of disruptive behaviors. In some cases, the students remain out of class for days or weeks, according to the complaint, and the problem is worse in small and rural districts.

Brown’s office didn’t immediately return a message seeking comment.

Marc Siegel, spokesman for the Oregon Department of Education, said he could not comment on pending litigation, but added in a statement that the department is “committed to equity and excellence for every learner.”

The state has made a handful of efforts to reduce the use of shortened days in the last few years. But Disability Rights Oregon attorney Joel Greenberg told The Statesman Journal that the situation is getting worse, not better.

“What’s happening is hurting a lot of children every day,” he said. “They have a disability, and that disability makes it hard for them to understand and regulate their own behavior.

“I would like other parents to understand what it might be like just because your child is different in some way and they are told they don’t belong in school … that they won’t get the same opportunities.”

The lawsuit was filed by a list of concerned families, attorneys and advocates, including Disability Rights Oregon, the National Center for Youth Law, the Council of Parent Attorneys and Advocates and the Bazelon Center for Mental Health Law.

The lawsuit says children as young as 5 and 6 are routinely excluded from attending a full school day with their peers because of their disability-related behaviors.

Some of these children receive as little as one or two hours of instruction a day instead of the six hours their classmates typically receive. One child Greenberg has represented was denied a full day before he even began attending school, he said.

When children are in school, instruction often takes place in a separate classroom where they have little opportunity to interact and learn with their peers, despite research that says they are far more likely to enjoy academic and social success when allowed to do so, the complaint says.

“It’s similar to what happens on a snow day or unannounced day off of school, only it goes on forever,” he said.

Under federal law, the state must ensure that all students receive an appropriate education without discrimination based on disability.

State law allows students to be placed on an abbreviated schedule in some instances.

In those cases, parents must have had an opportunity to meaningfully participate in the placement, and school specialists that help craft the child’s education plan must show they considered at least one other option. That team must also document the reasons why an abbreviated day is necessary.