Standards for commercial egg production vary greatly around the country. In most states, the egg-laying hens are crowded together tightly in “battery cages.” Each wire cage is about the size of a microwave oven, though slightly taller, and crammed with anywhere from four to 11 hens. But some states — including California, Ohio, and Michigan — have banned the use or new construction of battery cages. California’s Proposition 2, passed in 2008, requires that commercial laying hens be kept in spaces with enough room to stretch their wings.

It’s well past time to create a national standard that promotes more humane conditions everywhere. House Republicans and Democrats have introduced a sensible bill that would require labeling on all egg cartons to specify whether the eggs are from caged, cage-free or free-range hens. It would phase in over the next 15 years to 18 years requirements for larger cages (nearly doubling the space each chicken is provided), perches, scratching areas and nesting boxes. And farmers would be allowed to depreciate fully the equipment they already own before being obliged to buy new equipment.

The bill, amending the Egg Products Inspection Act, enjoys the support of the Humane Society of the United States, which has been a force behind improved conditions in the egg industry, and the United Egg Producers, which represents the farmers who raise nearly 90 percent of the eggs sold in America.

Yet the American Farm Bureau Federation, a trade group for farmers, the National Pork Producers Council, and the National Cattlemen’s Beef Association oppose the bill. They seem to fear that common sense and a humane regard for the well-being of farm animals will spread to their own industries.