Are the police watching you?

Ia police or sheriff’s department could buy a fleet of drones or a set of surveillance cameras to monitor the community its employees have sworn to protect, yet not tell anyone — not even the local government. The secrecy, law enforcement officials argue, is crucial to the effectiveness of the technology in fighting crime.

Yet it’s also the reason state lawmakers should pass a bill by Sen. Jerry Hill (D-San Mateo) that would bring some badly needed transparency to the use of surveillance by state and local law enforcement agencies.

Improving technology is making it steadily easier for the police to collect, analyze and warehouse data about people. For example, automated license-plate readers can keep a record of every car that passes. Cellphone antenna spoofers can log the time and place of every phone that comes within range. Body cams record just about everything a cop sees. Facial recognition technology can identify people in photographs. Drones can capture images of everyone at a rally.

These capabilities can certainly make it easier to enforce the law. But there’s a tradeoff: The more we use surveillance in pursuit of security, the less freedom we have from scrutiny by the government. And the more information the government collects, the greater the risk it will be abused, stolen, or exploited for purposes other than the ones that justified its collection.

The state Legislature passed laws in 2015 that require law enforcement agencies to create and disclose policies governing how they would use license plate readers and cellphone interception devices. That same logic informs Hill’s SB 21, which would require police and sheriff ’s departments to create and make public updated policies before they buy any new technology designed to monitor and collect data about an individual or a group.

Hill’s measure wouldn’t give local governments more power over a law enforcement agency’s tactics or spending than they have today. But it would at least encourage a public discussion of whether and how surveillance technology will be employed. It also would require reports every two years revealing how often a surveillance technology is used, how much it cost and how effective it was — how many cases it helped solve or close. Finally, it would bar agencies from selling or sharing the data collected with anyone other than another law enforcement agency.

The bill leaves agencies an enormous amount of flexibility. But it would prevent them from amassing the technologies in secret. Opponents argue that the disclosure would help criminals circumvent the surveillance, but that’s no justification for allowing law enforcement to make these hidden investments — cops and criminals have long been locked in a game of technological cat and mouse. The residents of a community should have a say in how intensively they will be monitored, and that can’t happen if they don’t know how they’re being watched.