If you look anywhere near the age of 21, chances are you'll be carded before making any alcohol purchase. But how does that work when everything is automated?
The grocery industry has no hard numbers but estimates one out of five transactions is done at self checkout scanners in grocery stores where they're available.
The Fresh & Easy chain just opened in the Bay Area and is 100 percent self checkout.
"We have over 2.3 million youth that are drinking in California every year and self checkout is too easy of a way for them to beat the system," says Bruce Lee Livingston of the Marin Institute, an alcohol industry watchdog.
This is how the system works. When an alcoholic product is scanned, the system is supposed to lock up. In some stores a light even goes off. A clerk is alerted to come over and check for ID before the transaction can be completed.
The California Grocers Association says the system works.
"We believe the protections are in place ensuring that underage individuals aren't able to manipulate the system," says Dave Heylen of the CA Grocers Association
We decided to find out for ourselves. 7 On Your Side sent 22-year-old Blanca Garcia to purchase beer at Safeway, Lucky and Fresh & Easy.
At Safeway, the system failed to lock up, but a clerk did come to talk to her.
"She didn't ask for ID. She didn't ask me how old I was. She didn't ask for nothing. She just reminded me to grab my change and I walked out of the store," says Garcia.
Safeway declined to comment on camera, but in an e-mail told us it's "continuing to investigate this incident and hopes to determine if it was a computer or human error."
7 On Your Side went to a second Safeway. The system did work properly there, as it did at the one Fresh & Easy and Lucky they visited.
Safeway insists its policy is to card anyone who looks under 30. Garcia says students who drink will try to get away with what they can.
"Trying to get away with not being carded. So if they're under 21 just trying to see, push the boundaries on the self checkout," says Garcia.
Our small sample roughly matches that of two larger studies.
In 2009, UCLA researchers found that out of 97 alcohol purchases in Southern California, stores didn't check or ask for ID one out of five times or 20 percent.
A similar San Diego state study in 2010 found that out of 216 attempts, the self check scanners in southern California failed to flag the alcohol purchase nine percent of the time, and no ID was required more than eight percent of the time.
San Francisco Assemblywoman Fiona Ma introduced a bill that would prohibit the sale of alcohol at self checkout scanners.
"ID's are not being checked. We feel this is a loophole that's going to make the situation worse and we'd like to make sure anyone who buys alcohol needs to be ID'd at the checkout stand," says Ma.
But the Grocers Association says the bill is unnecessary.
"No retailer out there is going to want to lose their alcoholic beverage license. That's something that's very important. They're going to do everything they can to protect that," says Heylen.
Alcoholism prevention experts have a different take.
"If it's completely self checkout, it means there's no humans involved. It's just kid vs. the machine and I think eventually the kid will win," says Livingston.
The Grocers Association questions the validity of both the UCLA and San Diego State studies. The bill is scheduled to be heard by the Appropriation Committee on Wednesday, May 4.