LAS VEGAS >> A judge today ordered a teachers union to put an end to teacher absences that have forced Las Vegas-area school closures and that she said are “very clearly a strike,” amid a contract battle in a state where it is illegal for public employees to walk off the job.

Since Sept. 1, unexpected staff shortages have led eight schools to cancel classes for the day and two others to combine classes, according to the Clark County School District, the largest in Nevada and the fifth-largest in the nation with about 295,000 students. One school had 87% of its teachers call in sick on the same day.

“The idea that this can be ignored, that these are sick call-outs, and that they are actually due to someone being sick is preposterous,” Clark County District Judge Crystal Eller said in a hearing. If the union fails to stop the strike, penalties could include a fine of up to $50,000, as well as jail time or termination for striking members and union leaders.

The Clark County Education Association, which represents about 18,000 teachers, has said it isn’t responsible for the wave of absences that swelled Tuesday with the unexpected closure of four more schools.

The district, which has close to 380 schools, is already facing more than 1,100 teacher vacancies. The education association, however, says vacancies are almost double that if you factor in open positions currently filled by substitutes.

Union leader John Vellardita said after the hearing that he “respectfully” disagrees with the judge’s order. The union will appeal to the state Supreme Court.

The tense contract negotiations are unfolding at a time when labor unions across the country are challenging how workers are treated, from Hollywood writers and Detroit auto workers to Los Angeles school employees and Las Vegas Strip hospitality workers.

The judge said she was “extremely sympathetic to how difficult the situation is” but the law is clear that Nevada public employees cannot strike.

“Obviously, we want our students to have good teachers. We want our teachers and our office staff to be fully and completely compensated, to have the benefits that they deserve,” Eller said, while also urging the school district to put in what she called a “good faith” effort to reach a deal with the union.

Negotiations have been underway since March over issues such as pay, benefits and working conditions, but grew tense this summer when the union threatened to take action if a contract wasn’t reached before the 2023-24 school year. Those actions included teachers refusing to work more hours than their contracted workday.

“It is simply not believable that Defendants would threaten targeted work actions for months and have no involvement when those work actions come to pass through their own members’ conduct,” the school district said in a motion filed this week asking the judge to halt the strike.

Negotiations resumed this week, but ahead of tosday’s hearing, the school district announced that they were at an impasse, saying arbitration was now “the only way” to resolve the fight after 11 unsuccessful bargaining sessions. It called the union’s demands “budget-busting.”

Union leaders said they welcome “a third set of eyes” during arbitration but expressed frustration over what they said is likely to be a lengthy process. In the meantime, teachers will be covered by their existing contract.

The union wants 18% across-the-board pay raises over two years: additional compensation for special education teachers and teachers in high-vacancy, typically low-income schools; and increased pay for teachers working extended-day hours at certain campuses.

The district said its final offer before declaring the impasse included a 9% salary increase during the first year of a new contract, a new pay scale that it said emphasizes college education and years of experience, and other incentives for special education teachers and hard-to-fill positions.

The teacher shortages have affected thousands of students.

Andrea Brai’s son is enrolled at Sewell Elementary, where 72% of licensed staff members called in sick last Friday, according to the district. She told KVVU-TV that day that students’ needs shouldn’t fall by the wayside amid the contract dispute.

“When you become a teacher,” Brai said, “you should go into this profession with that in mind.”