LA Unified, the nation's second-largest school district with more than 600,000 students, closed for in-person instruction for more than a year during the pandemic.

Although LA Unified dropped its COVID vaccine mandate for school staff almost a year ago, a lawsuit accusing the district of violating workers rights can still move forward, the US Ninth Circuit Court of Appeals ruled in June.

The 2-1 ruling revived a case that a lower court had dismissed.

The judges in the 2-1 majority wrote that this case was different because they found LA Unified demonstrated a pattern of withdrawing and reinstating its vaccination policies over the course of the lawsuit.

The plaintiffs alleged that the vaccines do not prevent somebody from becoming infected with COVID-19 and characterized it as a treatment rather than a traditional vaccine.

They argued that by requiring employees to get the COVID shot, the school district was interfering with workers' rights to refuse medical treatment.

"No one with any credibility would tell you that the vaccine prevented COVID or stopped the spread," said John Howard, a San Diego attorney who argued the case.

The CDC says COVID-19 vaccines are effective at protecting people from getting seriously ill, being hospitalized, and dying.

The school district can appeal the ruling to a larger panel of judges on the Ninth Circuit.

If the new ruling stands, the lawsuit would return to the US District Court for Central California and Los Angeles for further arguments.

Lindsay Wiley, a law professor at UCLA and Director of the school's Health Law and Policy Program, said the judges' finding against a government intervention is extremely rare.

"The ruling could have a chilling effect on government attempts to require vaccines in the future," Wiley said.

Governments should be careful to build the evidence base for their vaccination requirements, which are increasingly challenged by well-financed anti-vaccination groups in court.

With CalMatters, I'm Carolyn Jones.