Stephen’s teachers started sending him to the separate room when he was in first grade.

Now 10, Stephen has been diagnosed with autism and anxiety. His mom said that when he got frustrated and behaved in ways teachers found disruptive – breaking pencils, blurting out or crumpling paper – educators swiftly removed him from the classroom, sending him to a room where he would sit the rest of the day without access to school work.

Sometimes the school simply sent him home for the day – it happened more than 80 times by the time Stephen reached fifth grade, his mom said. Eventually, school staff started urging his mom to agree to place Stephen in a separate classes exclusively for students with disabilities where they said he’d be “happier”.

His mom believes Stephen’s race makes him a target. Students called him “the dumb black boy” and teachers were quick to see him as the problem, she said.

Lawyers and education advocates say Stephen’s story is painfully familiar in Sacramento, especially for black students with disabilities.

In California’s capital city, nearly half of the district’s 6,000 students with disabilities are separated from their peers, according to a lawsuit against Sacramento city schools filed in federal court earlier this month, in violation of federal law that protects students’ equal rights to education.

We’ve known for 65 years that separate is inherently unequal Bridget Claycomb

Along with two other students, all of whom are black and have been diagnosed with a disability, Stephen is a plaintiff in a suit that argues the Sacramento city unified school district is systematically discriminating against students with disabilities by excluding them from the classroom then segregating them in separate schools and classrooms without access to the same rigorous, educational material as their peers – settings where they’re more likely to be physically restrained than to graduate.

Bridget Claycomb, an attorney for Disability Rights California, said the district’s practice of isolating students with disabilities is unlawful and unethical.

“We’ve known for 65 years that separate is inherently unequal,” she said, referring to the Brown v Board supreme court decision that established racial segregation in schools as unconstitutional.

“There is an othering that’s happening. These children see a system that is built for most students but not for them. So they begin to internalize that they are not deserving of a quality education,” Claycomb said.

Federal law requires public schools to educate students in mainstream classrooms, wherever possible. Parents and community members in Sacramento say the school district has known for years its practice is problematic but has done nothing to change it.

Lawyers and advocates say the segregation of students with disabilities is only one example of the ways in which Sacramento schools excludes certain students. A 2018 report by researchers from San Diego State and UCLA found that Sacramento suspends black students more often than any other school district in the state.

Black and white students represent 15% and 16% of the district’s 47,000 students, respectively, but in 2018 black students accounted for nearly 50% of all suspensions.

And in Sacramento, black students with disabilities are suspended more often than any other group. They’re 15 times more likely to be suspended than their white peers without disabilities, according to the lawsuit.

A spokesperson for the Sacramento city unified school district declined to comment, citing pending litigation, but wrote in a statement: “Let it be clear that we will not tolerate any form of discrimination in our schools and are taking these allegations very seriously. We will review the complaint once it is sent to us.”

Experts and education advocates have long argued that out-of-school suspensions increase the likelihood students will later drop out of school or tangle with the criminal justice system.

California over the past 10 years has taken steps to curb the use of out-of-school suspensions. Between 2012 and 2018 numbers fell by nearly half – from 710,000 suspensions a year to 363,000.

Last week, the California governor, Gavin Newsom, signed a bill that limited the use of “willful defiance” – a catchall reason for suspending students for infractions as small as wearing hats or using cellphones.

The California state capitol building in Sacramento. City schools suspend black students at a rate much higher than that of white students. Photograph: Salgu Wissmath/The Guardian

But while suspensions have dropped for all students, black students in California have a suspension rate of 9.4% – more than triple the rate of white students – a problem that advocates say goes back to the implicit bias of educators. (In Sacramento, black students are suspended at 16% – more than five times the rate of white students.)

Antionette Dozier, an attorney for the Western Center on Law and Poverty, one of four legal organizations representing the students, said it is a familiar issue but one that is starkest in the state’s capital.

“This is a statewide problem. However, Sacramento is probably the most egregious in terms of racial segregation and the treatment of black students,” Dozier said.

Across the country black students with disabilities are suspended more often than any other group, said Dan Losen, the director of the Center for Civil Rights Remedies at UCLA and a leading researcher on exclusion and discrimination in school.

Historically, he said, black students have been overdiagnosed as having emotional or behavioral disabilities – a diagnosis that indicates students have trouble controlling or expressing emotions – which then becomes grounds for removal from the classroom.

This is a statewide problem. [But] Sacramento is probably most egregrous in terms of racial segregation and treatment of black students Antionette Dozier

By law, educators need to consider whether misbehavior is a result of a disability when deciding how to respond.

“[Students] are not supposed to get kicked out of school for behavior they can’t control. Morally, that’s wrong. And legally, that’s wrong, too,” Losen said.

Legally, schools are supposed educate students with disabilities in mainstream classes whenever possible, but in Sacramento disabilities are ostensibly cause for placing students in separate classrooms and separate schools called “nonpublic schools”, which offer less rigorous curricula than traditional schools.

Kurtis, an 11th-grade student named in the lawsuit, is an avid reader, given to sci-fi novels, his attorney says. He daydreams about taking part in spirited classroom debates about books. But discussions like that don’t happen at the nonpublic school Kurtis attends.

Kurtis didn’t choose to attend the school. Over his protests and the objection of his guardian, his attorney said, school officials in Sacramento sent him there because he has a mental health condition. Now Kurtis feels hopeless and trapped in a school devoid of learning.

Few students in nonpublic schools make it to graduation. Between between 2008 and 2017, only a single student graduated meeting the eligibility requirements for the University of California, according to the lawsuit.

And these separate programs are disproportionately populated by black students. Even though black students make up 15% of the school district’s population, in 2018 they represented almost 38% of the population at the school district’s separate school for students with disabilities.

Plaintiffs in the current lawsuit aren’t the first to raise alarms over the district’s special education program. An audit released in 2017 highlighted the issues at play in the lawsuit and recommended actions to resolve them.

“It’s been two and a half years since that report was published and the district has taken no meaningful action,” said Darryl White Sr, the chair of the black parallel school board, a group that advocates for black students in Sacramento. “It’s clear that it’s not been given the priority it deserves.”

White said the black parallel school board started pushing for change years ago, after it held a community meeting on the way the school district treated black students with disabilities.

“We were floored by the number of people we had, and we were floored to realize that everybody had a story to tell. And those stories were very difficult to listen to,” White said.

The Disability Rights California attorney Bridget Claycomb said students in Sacramento have no more time to lose.

“We’ve named a few clients, but this is happening to so many students. And they can’t wait any longer. They needed the district to be better long ago,” she said.