IN A JUNE segment on “The Colbert Report” about Rep. Steve King’s (R-Iowa) amendment to the farm bill, comedian Stephen Colbert mocked Mr. King’s views by stuffing a rubber chicken into a paper towel tube and rolling it across the top of his desk. “See,” Colbert told his audience, “free range.” It was a comic but telling point.

Citing the commerce clause, Mr. King’s Protect Interstate Commerce Act, which the House passed in its version of the farm bill this summer, would repeal state laws dictating production standards for agricultural goods produced out of state. In particular, Mr. King was targeting a California law barring the sale of eggs produced under conditions cruel to hens.

Mr. King criticized the law for compelling producers nationwide to spend billions to meet large-market California’s production standards, a consequence the representative aims to halt, lest “radical organizations” create “a network of restrictive state laws that will slowly push agriculture production towards the demise,” he said in a May statement.

If approved by the Senate after the summer recess, Mr. King’s reactionary amendment would precipitate a disaster. Not only would laws regarding animal cruelty be upended, but so would laws protecting the environment, workers’ rights and public health, because Mr. King’s amendment bars any state-imposed condition on agricultural products. The Congressional Fire Services Institute wrote to leaders of the House and Senate agriculture committees to express its concern that Mr. King’s amendment would overturn state laws requiring cigarettes to be fire-safe.

Mr. King claimed that his act will prevent organizations such as the Humane Society and People for the Ethical Treatment of Animals from “establishing a patchwork of restrictive state laws aimed at slowly suffocating production agriculture out of existence.” In fact, such state laws are relatively few, modest and essential. The California law that Mr. King objects to calls for cages that allow chickens to spread their wings, turn around and lie down. It is one of nine state laws protecting farm animals, including pigs, cows and chickens, from spending their whole lives in containers only slightly larger than their bodies. Mr. King’s amendment would likely eliminate these safeguards in one fell swoop.

Mr. King is notorious for his lack of sympathy for animal rights activists and his shocking partiality for dogfighting, but his amendment has consequences more far-reaching than the welfare of hens. His senseless act would upend decades of state regulation that protect the people who work in the agriculture industry and the industry’s products, to all of our detriment. Deleting the act would create one more hurdle for Congress when it attempts to pass the farm bill in September, but the cost of the amendment’s passage is not worth paying.