Soon after starting his junior year last month at Barbers Hill High School in Mont Belvieu, Texas, Darryl George was separated from his classmates because of the way he wears his hair, his mother and a lawyer said.

Since the term began on Aug. 16, Darryl, a 17-year-old Black student, has received multiple disciplinary notices that have culminated in more than a week of in-school suspension, where he sits on a stool in a cubicle and work is brought to him, according to his mother, Darresha George. Each morning, he is asked by officials at the school, about 30 miles east of Houston, whether he has cut his hair yet, she said.

He has not.

“He is actually getting singled out,” said Ms. George. “They are personally stopping him, ‘Did he cut his hair?’ Asking him at the door.”

Darryl has locs, or long ropelike strands of hair, that he pins on his head in a barrel roll, a protective style that reflects Black culture, Ms. George said. On Aug. 31, about two weeks after school started, school officials told her that his hair length, even though pinned, violated the dress code.

“I was told that every day Darryl comes to school, he would be put in in-school suspension because his hair has not been cut,” she said. “Even if pulled up in buns or neatly pulled back, because when let down it is below his earlobes and eyebrows.”

Supporters of the family, including legislators and activists, have called the suspension alarming, saying that it could test a new state law called the CROWN Act. The law, which Gov. Greg Abbott signed in May, says, in part, that any dress or grooming policy adopted by a school district “may not discriminate against a hair texture or protective hairstyle commonly or historically associated with race.” The law does not specifically mention hair length.

The Barbers Hill Independent School District’s dress code mandates that a male student’s hair “will not extend below the eyebrows, below the earlobes or below the top of a T-shirt collar.”

A district spokesman, David Bloom, said that the dress code and suspension were “not in conflict” with the CROWN Act because the code permits protective hairstyles, if the hair would not go beyond the permitted length when let down.

“The vast majority of hair code violation punishments — I.S.S. or more severe — have been handed down to white students,” Mr. Bloom said, using the acronym for in-school suspension, where, he said, students are kept in a classroom staffed by a teacher, and sit at desks separated by partitions so as not to disturb one another.

The school informed Ms. George of Darryl’s suspension just one day before the law took effect on Sept. 1, she said.

Even though the CROWN Act does not specifically mention hair length, Darryl’s supporters have said the district’s move violates the spirit of the law. Candice Matthews, a civil rights activist and vice chair of the Texas Coalition of Black Democrats, said that braids, locs and twists need to be long to protect the hair.

“It is a hairstyle that is cultural in nature,” she said.

At least 23 other states have adopted similar laws banning discrimination based on race-based hairstyles in the workplace and public schools.

On Sept. 8, the Texas Legislative Black Caucus sent a letter to the district superintendent, Greg Poole, and the school principal, Lance Murphy, urging the district to clear Darryl’s record and warning that the suspension could set a “dangerous precedent.”

“The school is arbitrarily coming up with something else, saying that it’s really not the hair, it’s the length,” said State Representative Ron Reynolds, a Democrat and chair of the caucus.

State Representative Rhetta Andrews Bowers, a Democrat and the primary author of the CROWN Act, said she was inspired by the Crown Coalition, which advocates adoption of the law in other states, and by DeAndre Arnold and Kaden Bradford, cousins who attended high school in the same district as Darryl and were suspended for the length of their dreadlocks in a case that garnered national attention.

“We anticipated that even with the passage of the legislation that there could possibly be incidents,” she said. “We knew that it was largely going to be education and awareness making people understand. We are still on that path.”

Darryl’s case is not the first to test the new law. In August, Katheryn Huerta, the mother of an elementary school student in Mabank, Texas, cited the CROWN Act when she was told that she would have to cut her son’s long hair. Ms. Huerta told WFAA-TV, a local ABC affiliate, that her district later relented, saying she could put her son’s hair in braids and a bun.

A lawyer for Ms. George, Allie Booker, said that Darryl had been given until the end of the week to comply with the school’s dress code or he could be placed in a disciplinary alternative learning program. Ms. Booker said she is considering legal action.

“We are not cutting his hair,” Ms. George said, “because that is part of his culture, that is his roots. It is like cutting off a part of him.”