Democratic State Assemblywoman Fiona Ma wrote the law…which she says is intended to make it harder for teenagers to get beer, wine and hard liquor at self-service checkouts. 

"It is very easy to either trick the system; clerks don't come over to check a person's ID; easy to swap certain bottles out; or just not even scan a product all together."

But the California Grocers Association calls the law a solution looking for a problem. The group's president Ron Fong says safeguards were already in place.

"When you approach a self-assisted and you purchase alcohol it locks the system and it requires a human interaction to come over and do a visible check to see if you're over age."

The new law is supported by Mothers Against Drunk Driving and the California Police Chiefs Association.