Alcohol sales will no longer be allowed at automated checkout counters after Gov. Jerry Brown signed a law Sunday to ban the practice.

As of Jan. 1, 2012, all alcohol sales must be processed by a cashier. The bill’s author, Assemblywoman Fiona Ma (D-San Francisco) called it a protection against minors obtaining alcohol illegally.

The bill received backing from law enforcement groups and Mothers Against Drunk Driving.

Opponents said it was a transparent effort by grocery workers’ unions to protect jobs against the automated checkout machines.

Republican Gov. Arnold Schwarzenegger vetoed a similar bill, saying, "It is unclear what problem this bill seeks to address."