Now they are urging state legislators to spell out what confinement methods would be allowed for their laying hens.

The outcome could have a major effect on how eggs are produced -- and the prices charged to consumers in California.

Already, Assemblyman Jared Huffman, D-San Rafael, is pushing a bill that would require out-of-state egg producers to comply with the hen confinement rules that California farmers will face under Proposition 2. As part of that legislation, the state's egg producers are asking for clearer confinement rules.

The 2008 initiative won the approval of state voters by the lopsided margin of 63 to 37 percent. The law takes effect in 2015.

The egg farmers say they need guidelines now that essentially spell out the minimum amount of space they must provide for each hen. They contend that the law doesn't specifically outlaw all cage systems, and some farmers are seeking a hybrid arrangement that falls somewhere between the current cage and cage-free systems.

Arnie Riebli, a major egg producer in Petaluma and president of the Association of California Egg Farmers, said the farmers are willing to abide by the initiative. Nonetheless, he said, "there was nowhere in there that it said cage-free is the law of the land."

However, leaders for the initiative's main proponent, the Humane Society of the United States, accuse the egg farmers of double talk. During the campaign, the leaders said, the entire debate concerned whether to force the farmers to switch to cage-free operations.

"Now that Prop. 2 is law, the egg industry is trying to punch a hole in it, undo the will of the voters, and embrace its newfangled, post-election interpretation," Wayne Pacelle, the society's chief executive, wrote Thursday in his blog.

Huffman said he wrote his Assembly bill to create a uniform standard for all farmers who provide eggs to the Golden State. He maintained that California regularly places restrictions on out-of-state products sold here, including foie gras, makeup and jewelry.

Huffman called it reasonable for the Humane Society to work to protect Proposition 2 from being watered down. But he also found it reasonable for the egg farmers to obtain clear standards before they spend millions of dollars on new confinement systems.

"I'm sympathetic to their need for more certainty so they can go out and make the investments they need to make," Huffman said.

He expressed reluctance to amend his current legislation, AB 1437, because he said he had made a commitment to both sides that he wasn't "going to reopen the Prop. 2 battle." He intends to meet with both sides this week.

The initiative, said Huffman, is "fairly ambiguous." Asked if it would allow some sort of hybrid system, Huffman replied, "As I read Prop. 2, it's not even clear to me that cage-free would comply."

All sides agree that the law doesn't specify a minimum amount of space for each bird. Instead, it sets forth a performance test, essentially requiring that a hen must be able to extend its wings without being forced to touch its enclosure or another bird.

Paul Shapiro, senior director for the humane society's factory farming campaign, said his organization has yet to find a commercially made hybrid system, sometimes called a colony system, that gives the birds the space needed to meet that test.

"The only way to do that is in a cage-free system," he said.

Jennifer Fearing, an economist for the humane society, said "the Legislature lacks the authority" to modify or clarify the initiative. The society, she said, has offered to work with egg producers to get clarity by seeking a state attorney general's opinion.

As in last fall's campaign, the two sides fiercely dispute the economics of the various systems.

Fearing maintained that the farmers wouldn't get any extra revenue and would face added expense from a hybrid system. Instead, she said, they should seek the extra income possible by selling a specialty product: cage-free eggs.

But Riebli, a partner in Petaluma's Sunrise Farms, producer of a million eggs a day, estimated that a hybrid colony system would boost his expenses by only 5 to 12 cents a dozen, an amount he maintains he could reasonably expect to recoup from consumers. But he estimated that conversion to a cage-free operation would increase his expenses by 40 to 50 cents a dozen.

"There's no way that you can recover your investment," he said.

You can reach Staff Writer Robert Digitale at 521-5285 or robert.digitale@pressdemocrat.com.