By Daniel Wiessner

California's top state court has ruled that employers cannot be held liable when workers contract COVID-19 on the job and spread it to their household members, siding with business groups who warned of a potential flood of litigation.

The seven-member California Supreme Court on Thursday unanimously ruled that allowing so-called "take home COVID" claims could encourage businesses to adopt precautions that slow the delivery of services to the public, or to shut down completely during pandemics.

Corby Kuciemba had filed the lawsuit, saying she became seriously ill when her husband contracted COVID at his job with Victory Woodworks Inc in 2020 and passed it to her.

The court said a ruling for Kuciemba would turn every employer in California into a potential defendant, even when they had taken reasonable steps to prevent the spread of the virus or when it is impossible to prove that employees contracted COVID at work.

"Even limiting a duty of care to employees' household members, the pool of potential plaintiffs would be enormous, numbering not thousands but millions of Californians," Justice Carol Corrigan wrote for the court.

Lawyers for Kuciemba and Victory Woodworks did not immediately respond to requests for comment.

The court took the case after the San Francisco-based 9th U.S. Circuit Court of Appeals last year asked it to decide whether California law recognizes negligence claims against employers when workers spread COVID to household members.

The 9th Circuit is considering Kuciemba's bid to revive her lawsuit after it was dismissed by a California federal judge. After Thursday's ruling, the 9th Circuit will most likely uphold that decision.

Business groups had argued that allowing take home COVID claims could prompt lawsuits by an infected employee's family and friends, and anyone infected by that circle of people, creating a never-ending chain of liability.

(Reporting by Daniel Wiessner, Editing by Alexia Garamfalvi and Richard Chang)