SACRAMENTO — California will loosen confidentiality rules that have barred public access to almost all police misconduct records, under a bill signed by Gov. Jerry Brown on Sunday.

Under SB1421 by Sen. Nancy Skinner, D-Berkeley, an officer who commits sexual assault, lies on the job by planting evidence or falsifying reports will no longer be shielded by California’s blanket protections that kept police personnel documents private.

The law, which goes into effect Jan. 1, also makes investigations and reports related to an officer’s serious or deadly use of force subject to the state’s Public Records Act. While all public employee personnel records are generally confidential, police had additional protections blocking even substantiated misconduct records.

Skinner introduced the police transparency measure in response to law enforcement shootings that have drawn protests around the country, including in Sacramento where two city police officers shot and killed Stephon Clark, a 22-year-old black man who was unarmed, in March.

Advocates for shedding light on police disciplinary records say it will increase trust between law enforcement officers and their communities.

“Law enforcement relies on trust with the communities they serve to effectively do their job,” Skinner said. “When incidents occur the public deserves to know that a thorough investigation has occurred and that police are held accountable.”

Brown also signed AB748 by Assemblyman Phil Ting, D-San Francisco, which will make it easier for the public to obtain body camera footage taken by a police officer. The bill requires law enforcement to release the footage or audio within 45 days of a critical incident.

“The governor’s signature on AB748 signifies a strong commitment to police transparency in California,” Ting said. “Public access to body camera footage is necessary to boost confidence and rebuild trust between law enforcement and the communities they serve.”

Melody Gutierrez is a San Francisco Chronicle staff writer. Email: mgutierrez@sfchronicle.com. Twitter: @MelodyGutierrez