California legislators on Tuesday introduced two bills aimed at improving access to mental health and addiction treatment by requiring health insurance companies to authorize some forms of treatment more quickly and to cover more comprehensive mental health services.

State Sens. Jim Beall, D-San Jose, and Scott Wiener, D-San Francisco, co-authored Senate Bill 854 and Senate Bill 855 — which both would apply to private health insurance plans only, and not to public insurance programs such as Medi-Cal, the joint federal and state health insurance program for low-income residents. The bills do not address how uninsured residents seek care.

SB854 would prohibit insurance companies from directing patients with substance use disorders to first try other forms of treatment — such as group therapy or step therapy — before covering medication-assisted treatment, or MAT, if MAT is what their doctor recommends. MAT is becoming a more common form of treatment for opioid addiction, in which patients are prescribed opioid medication — at lower doses that don’t induce a high — to wean them off of stronger opioids. It is done under the supervision of a physician and in conjunction with counseling and other behavioral health services.

SB855 would require insurance companies to cover all forms of mental health and substance use treatment that a patient’s doctor deems “medically necessary” — not just emergency or urgent services that existing federal and state parity laws require insurers to cover. The bills’ authors and health advocates say existing laws don’t do enough to ensure Californians get timely and comprehensive enough care for mental health conditions.

The California Mental Health Parity Act of 1999 requires insurers to cover services for severe cases of some mental health conditions, but not all types of treatments for all conditions, or substance use disorders.

“We have a huge, huge challenge in California, not just with our homeless population but with everyone, and we need better access (to mental health care),” Wiener said. “These bills will move us in that direction.”

The California Association of Health Plans, which represents public and private health insurers, said that the proposed legislation would create new mandates and that insurers already work with state regulators to comply with current parity laws.

“Mental health care is a high priority for health plans and we are fully committed to ensuring patients are getting the mental health services they need that are on par with medical and surgical care,” the group’s spokeswoman Mary Ellen Grant said in a statement. “Mental health parity is already the law of the land in California and California currently has regulators who are capable of overseeing our compliance with the law. The bills introduced today are less about mental health parity and more about creating new mandates. It is hard to understand how SB855 could be called a mental health parity bill when it sets forth a new system for medical necessity that is at a higher level than other medical services.”

Catherine Ho is a San Francisco Chronicle staff writer. Email: cho@sfchronicle.com Twitter: @Cat_Ho