Gov. Jerry Brown has signed a union-backed bill prohibiting grocery stores from selling beer, wine or liquor using electronic self-checkout lanes, Brown announced this morning.

Assembly Bill 183, by Assemblywoman Fiona Ma, D-San Francisco, was supported by labor and police chiefs, who said it could deter underage drinking.

Business groups and grocers said existing oversight is sufficient and blamed labor interests for trying to block Fresh & Easy, a nonunion chain that uses only staff-supervised self-checkout lanes.

Fresh & Easy said in a prepared statement Monday that "we are disappointed that politics has prevailed over solid judgment."

Brown also vetoed legislation that would have required local governments to study the economic impact of proposed Wal-Mart and other superstores before approving them.

Senate Bill 469 by Sen. Juan Vargas, D-San Diego, would have required the studies to be paid for by project applicants.

"While I recognize that the merits of large-scale projects need to be carefully considered, plenty of laws are already on the books that enable and in some cases require cities and counties to carefully assess whether these projects are in a community's best interests," the Democratic governor said in a veto message. "This bill would add yet another layer of review to an already cumbersome process."

Vargas' bill had been assailed as a union-inspired effort to block development of non-union retail stores.

The California Retailers Association praised Brown's veto. "This veto clearly preserves local authority to decide what businesses they want in their communities and empowers them to bring in more jobs, economic activity and revenue.," Bill Dombrowski, the group's president, said in a statement.

Vargas said he was undeterred by Brown's veto. "Research continues to show that supercenters cause business districts to suffer, significantly decrease the net number of jobs and often rely on taxpayer-funded government services, like Medicaid, to provide healthcare for their employees," he said in a statement. "I will continue to work to make sure that our communities know the truth about these supercenters and how they claim to be creating jobs when actually they are destroying them."