The law affects people caught with an ounce or less of marijuana.  Until now, that's been a misdemeanor, which includes the option of a trial.  Going forward it will be an infraction.  The punishment - a 100 dollar fine - remains the same.  The big difference is the cost to the state, says Democratic Senator Mark Leno.  He wrote the bill:

When Governor Arnold Schwarzenegger signed the bill, he also highlighted the cost savings.  Schwarzenegger talked about his decision during an appearance on NBC's Tonight Show with Jay Leno:

"I think the laws that we passed, they were good.  It makes it from a misdemeanor to an infraction and no one cares if you smoke a joint or not."

Stephen Gutwillig is with the Drug Policy Alliance.  He supports the new law - but says it didn't go far enough.  He says young African-Americans and Latinos are disproportionately charged with marijuana possession and the new law makes it harder to track that:

 "Misdemeanor arrest data is available from the Department of Justice.  But not data on infractions."

The conservative group Save-California-dot-com opposes the new law, arguing that it invites more young people to become addicted to marijuana.  SOC