California lifted indoor masking requirements for fully vaccinated residents Wednesday, meaning many in the state will be free to go most public places without a face covering if they’ve gotten their shots, KTLA sister station KWSB in San Diego reports.

But that shift in the rules has raised a thorny question: How will officials confirm everyone who goes maskless in public places is following the rules? The state never implemented a centralized “vaccine passport” system, and most people aren’t used to showing proof unless they’re traveling internationally, attending certain events or, in some counties, partaking in indoor activities like dining or going to a movie theater.

In short, the answer for most cases is going to be the “honor system.”

State health officials said Wednesday that businesses and other public places are not required to check vaccination status before allowing people to congregate without a face covering. There is no formal system for doing so, and most local businesses chose not to check customers last summer, when there were also tiered rules for masking.

If businesses have “prominently displayed signage prior to entry explaining the requirements for unvaccinated individuals,” the state says, anyone who is not wearing a face-covering is assumed to be “self-attesting” to their vaccinated status.

With that being said, businesses and event organizers can still choose to require proof of vaccination, the California Department of Public Health confirmed by email. If you want to go without a mask in those spaces, staff members are within their rights to ask for proof. Businesses also have the right to voluntarily keep face-covering requirements in place altogether.

Even if you’re fully vaccinated, it might be a good idea to keep your vaccine card or a mask handy on the chance that you’re visiting somewhere that has its own policy.

If you’re somewhere where those rules aren’t in place, San Diego County spokesperson Michael Workman said there are no plans to involve local law enforcement or other officials in checking vaccination status among unmasked people.

While many counties are joining San Diego in adopting California’s new policy, it’s also worth noting that local governments are permitted to opt for stricter rules. In Los Angeles County, for example, face coverings remain required for all people indoors.

As a final caveat, keep in mind the following places where masks are still required regardless of vaccination status:

  • On public transit like planes, ships, ferries, trains, subways, buses, taxis, and ride-shares
  • In transportation hubs like airports, bus terminals, marinas, train stations, seaports or other ports, subway stations
  • Indoors at K-12 schools and childcare centers
  • Emergency shelters and cooling and heating centers
  • State and local correctional facilities and detention centers
  • Homeless shelters
  • Long term care settings and senior care facilities

School masking rules will be closely watched in the weeks to come. Some parents protesting in San Diego County this week are pressuring officials to lift their face covering policies for schoolchildren, especially in the wake of last weekend’s massive Super Bowl gatherings in Los Angeles.

You can read more on state masking rules in this Q&A from the California Department of Public Health.