Veterans who commit a crime in California and have a mental illness related to their military service already had the option to get treatment instead of prison time.

But they weren't always making that choice.

CONATY: "We needed something to give them a reason to go into treatment."

Pete Conaty spoke for several veterans groups at the state Capitol last year in support of the measure.

CONATY: "This would erase their guilty plea, and erase their offense if they successfully complete treatment."

Cory Salzillo of the California District Attorneys Association says the new law is unnecessary.

SALZILLO:"It was unclear that the bill provided any actual relief that wasn't already provided by current law."

Supporters of the measure say there are nearly 2 million veterans in California, and nearly thirty thousand are incarcerated in the state.