An overwhelming majority of Massachusetts voters, nearly 78 percent, approved a ballot initiative Tuesday that will require vendors to ensure that every egg and every cut of pork or veal they sell in the state comes from animals that were given ample space to move around.

In regulating sales of animal products on the basis of how they were raised, rather than regulating the farming practices alone, the animal welfare measure is the first of its kind to be passed by referendum in the United States. It will likely influence practices in other states that hope to do business with the 6.8 million consumers who live in Massachusetts, and it could help to shape attitudes nationwide as American eaters grow less tolerant of subjecting farm animals to harsh treatment.

"It's a historic advancement for animal welfare," Paul Shapiro, the policy vice president for the Humane Society of the United States, told The Boston Globe. "To have an entire state declare that cruelty to farm animals is such a pressing matter that it is establishing a retail standard to ensure that animals are able to at least engage in basic movement really sends a powerful signal."

This increasing social concern about the treatment of animals raised for food can be described as part of "The new ethics of eating" in the United States, as The Christian Science Monitor's Fabien Tepper wrote in 2014:

The conscience of consumers increasingly aware of the treatment of animals that become their burgers and chicken fingers has thrown a wrench in the gears of industrial farming, which has raced since the end of World War II to raise and slaughter animals faster and more efficiently, without much regard for their welfare.

There are people on all sides of the issue – farmers, distributors, government regulators, animal welfare advocates, and research scientists – who concur that animal welfare is now an established and growing ethic in the US production of food. The view that food animals are simply a commodity is yielding increasingly – albeit haltingly – to the perception that these animals are also sentient beings deserving of more-humane treatment.

That trend was behind the decision by the nation's fourth largest chicken producer, Perdue Foods, to improve the living conditions of their more than 700 million chickens – a plan that made Perdue the first major US company to promise it would quit using the industry's standard slaughtering method in favor of a procedure deemed more humane. Instead of dangling the birds upside down before stunning and killing them, Perdue will use gases in a controlled atmosphere.

Opponents of the new Massachusetts law, which will take effect in 2022, argue that it will drive prices skyward, with estimated price increases ranging from 12 cents per dozen eggs to nearly $1 per dozen, the Globe reports.

Since the farming industry argues that its current practices are already safe and humane, some advocates for low-income people say the measure constitutes a social injustice.

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"It seems cruel for people who can afford expensive tastes to raise prices for those who struggle every day to feed their families," wrote Diane Sullivan, who managed the coalition that opposed the measure, in a Globe opinion piece. She called the measure "a regressive food tax."

In 2008, voters in California passed a measure to require that egg-laying hens be able to move around and spread their wings, and a law passed by the state's legislature to impose that same requirement on all eggs sold in their shells in California took effect last year, as The Washington Post reported. California faces a lawsuit from six other states that produce eggs, who argue the law is an unconstitutional restriction on interstate commerce.