California voters freed the state's egg-laying hens last fall, but Proposition 2 left a big loophole: Supermarkets could still sell eggs laid by caged birds in other states.
Now, animal-welfare advocates are backing legislation requiring every egg sold in California to be from a cage-free hen.
Assembly Bill 1437 would greatly expand the scope of the proposition, which is scheduled to take effect in 2015.
Economists predict Proposition 2, on its own, will drive up imports of cheap, conventionally produced eggs, pushing many in-state farms out of business.
If AB 1437 passes, though, it would make the entire California market – about 10 percent of the nation's eggs – cage-free. That huge demand, backers hope, would support California farms as they convert to cage-free production and drive some big egg farms elsewhere in the country to scrap their cages as well.
California now buys about a third of its eggs from other states.
The Humane Society of the United States, the force behind Proposition 2, says it hopes the California egg industry remains viable so that other states won't see a switch to cage-free hens as an industry-killer.
"This is an effort that we fully intend to extend to the rest of the country," said Jennifer Fearing, the group's chief economist.
No other state has restricted hen cages. Cage-free eggs are about 6 percent of the national market.
It's not clear how AB 1437 would alter egg prices.
Cage-free systems add a penny or two to the cost of producing an egg, according to a University of California study last year. The retail price difference between caged and cage-free eggs, though, averages well over $1 a dozen, according to the U.S. Department of Agriculture.
If cage-free eggs were the only type available in California, that spread would likely narrow to roughly the difference in production costs, said Daniel Sumner, an agricultural economist at the University of California, Davis.
California's egg industry has yet to take a position on AB 1437. The Association of California Egg Farmers is now focused mainly on getting state regulators to clarify what hen housing will be legal, spokeswoman Fiona Hutton said.
Proposition 2 requires only that hens have room to stand up, turn around and extend their wings without touching another bird. Farmers need more detail before investing in new equipment, Hutton said.
Cage-free systems give hens three main things: a nest, a perch and a place to take a dust bath. According to animal-behavior experts, hens act stressed when they don't have those basics.
A 60,000-square-foot barn with stacked cages can hold as many as 150,000 hens. Cage-free hens still live in crowded, indoor conditions, with as many as 30,000 birds in the same size barn.
While cage-free systems meet basic needs, they also tend to be more perilous. Hens get sick and injured more often, and die at roughly twice the rate of birds in cages, according to studies of egg farms in Europe.
AB 1437, authored by Assemblyman Jared Huffman, D-San Rafael, passed 65-12 in the Assembly last month. It's likely to be heard next in the Senate Food and Agriculture Committee, which is chaired by Sen. Dean Florez, D-Shafter, one of Huffman's co-authors on the bill.
Editor's note: This story has been changed from the print version to correct a reference to Proposition 2 as a ban on cages.