Lawmakers in eight states are expanding efforts to thwart secret videos of alleged animal welfare abuse in farming operations.

The so-called “ag gag” laws have been passed in Montana, North Dakota and Kansas, and similar legislation is proposed in Iowa, New York, Minnesota, Illinois, Indiana, Missouri, Nebraska and Utah.

Animal rights groups such as the Humane Society of the United States contend food safety will be compromised if abusive and unsanitary practices go unexposed.

“For politicians, it comes across looking like they’re trying to muzzle these groups,” says Wes Jamison, an associate communications professor at Palm Beach Atlantic University in Florida who studies animal rights activism. “It’s putting restrictions on citizen ‘gotcha’ journalism.”

Studies at Kansas State University and Purdue University suggest that stories about animal welfare have a significant, negative effect on meat demand, especially poultry and pork.

Lawmakers from farm states contend the video coverage is distorted and is merely an effort to force retailers to drop or pressure their suppliers.

While provisions vary by state, the bills generally aim to make it illegal to tape undercover video at livestock operations or obtain a farm job under false pretenses.

A proposal introduced last month in Nebraska would require cruel treatment to be reported within 12 hours, preventing those who go undercover of the time it takes to amass evidence, according to animal rights groups.

Some legislative efforts have triggered public backlash and legal questions about protection of free speech. A bill outlawing the taking of images at farms without an owner’s permission failed last month in Florida. Animal rights groups rallied against it, arguing trespassing laws already address such activity. Opponents also said the measure violated the First Amendment protecting free speech.

“Both the volume and immediacy of videos have increased,” Jamison says. “It’s a reaction by agricultural states to protect their agricultural base.”

He says farmers who have adopted welfare-friendly production practices are frustrated that the videos create a distorted impression of industry practices.

Such investigations used to be done to try to change consumer behavior; now the goal is to pressure retailers into forcing suppliers to change practices.

This report was excerpted from Bloomberg news service.