SAN FRANCISCO — The California Supreme Court sounded poised Tuesday to rule that employees have a right to be left alone by the union that bargains on their behalf.

Most of the justices sounded uncomfortable with the idea of requiring employers to disclose home addresses and phone numbers of employees who have opted not to join the local union. The National Labor Relations Board and California Public Employee Relations Board have ruled that unions are entitled to the information, but several justices seemed to think such disclosures collide with California’s constitutional right to privacy.

And a couple suggested that 21st century communication technology has changed the legal equation. Many people have abandoned "home" phone numbers for cell phones, Chief Justice Tani Cantil-Sakauye noted. "If you have a cell phone number you can send a text," she said. "And if you can send a text, you can f-l-l-a-a-a-m-e someone."

Justice Ming Chin suggested unions consider email instead of traditional mail. "There are ways for you to contact people other than knowing where they live," he told David Rosenfeld of Weinberg Rogers & Rosenfeld, representing SEIU Local 721.

"Some of us who get many emails think it’s very intrusive," Rosenfeld responded.

Meanwhile, a second case argued Tuesday sounded less promising for local governments. The justices sound entirely unmoved by the City of Long Beach’s plea to spare it from a class action based on an allegedly illegal utility tax it’s charging. The issue is potentially worth hundreds of millions to municipalities around the state facing similar class actions, attorney Michael Colantuono has argued for the City of Long Beach. But the justices suggested nothing in the relevant statutes foreclose such class actions. "The language couldn’t be clearer," Justice Joyce Kennard told him.

In the privacy case, County of Los Angeles v. Los Angeles County Employee Relations Commission, SEIU asked during bargaining for the personal contact information of several thousand employees who’ve elected not to join the union. Although they’re still required to pay dues, these non-members did not respond to union requests to provide their home addresses and phone numbers. SEIU wants to try to recruit them to membership, and to contact them if important job conditions like layoff notices or salary freezes arise. If an employee doesn’t show up for work for an extended period, Rosenfeld said, the union may want to pay them a visit to let them know their job could be in jeopardy.

Californians have a right to keep their contact information away from the general public, Rosenfeld said. But "we say there’s no reasonable expectation of privacy vis-a-vis your bargaining representative," particularly given that the unions are required by law to represent all employee interests.

He sought to reassure the court that in special circumstances — say, an employee in a witness protection program or a domestic violence situation — the union would not insist on the information, but argued the county must bargain over which employees meet that standard.

Justice Goodwin Liu sounded wary. "At what point can an employee say, ‘Really, I just don’t want any more contact?’" he asked Rosenfeld. In the age of do-not-call registries and no-junk-mail lists, "one might suggest the societal norm these days is to nip [unwanted contact] in the bud."

Calvin House of Gutierrez Preciado & House, representing the county, argued that when an employee is absent for several days, it’s often because they’re ill, so a visit from a union rep would be especially unwelcome. House said the union should use email — though he acknowledged the county doesn’t maintain employee emails in its database — voice-over-Internet, or "PR through the media."

Justices Carol Corrigan and Joyce Kennard expressed some reservations about the county’s position. For the county to be advocating employee interests against the union is "a strange set of circumstances, don’t you think?" Corrigan asked House.

And Kennard, like Rosenfeld, didn’t see email as the answer. "Some people think it’s a huge intrusion on privacy," she said.

But the court sounded likely to establish a balancing test that involves notice to the employees and an opportunity to either opt in or out of communication. "If they don’t take the initiative to affirmatively opt out," Justice Marvin Baxter said, "why should they be protected when you get into a balancing?"