SALT LAKE CITY -- A federal judge struck down a Utah law banning secret filming at farm and livestock facilities Friday as an unconstitutional violation of free-speech rights.

U.S. District Judge Robert Shelby wrote in his ruling the law appears tailored toward preventing undercover animal-rights investigators from exposing abuses at agricultural facilities.

Shelby said the state does have an interest in protecting the agricultural industry and a variety of ways to do it.

"Suppressing broad swaths of protected speech without justification, however, is not one of them," he wrote.

It wasn't clear whether the state would appeal the decision. Utah Attorney General's Office spokesman Dan Burton said Friday the office is reviewing it.

The law was passed amid a wave of similar measures around the country known as "ag-gag" rules, including one in Idaho that was struck down last year. That ruling is being appealed.

Animal Legal Defense Fund lawyer Matthew Liebman applauded the Utah decision and said it makes the laws passed elsewhere vulnerable to legal challenges.

"We're already eyeing which statutes to go after next," Liebman said.

The seven other states with similar laws are Kansas, Montana, North Dakota, Iowa, Missouri, Arkansas and North Carolina.

The state of Utah has argued the First Amendment doesn't allow people to enter private property under false pretenses and record however they want.

State attorneys say the law protects property rights and makes agricultural workers safer by barring unskilled undercover operatives from potentially hazardous places.

The Utah case, filed by animal-rights groups, was the first lawsuit in the U.S. to challenge one of the ag-gag laws.

It came after a woman was charged in 2013 when she filmed a front-end loader dumping a sick cow outside a suburban Salt Lake City slaughterhouse.

The case was dismissed because she was standing on a public street when she made the recording.

Charges against four animal activists from California who were cited outside a large Utah hog farm in 2015 also later were dropped because the farm didn't want to pursue them.

The measure made it a misdemeanor to enter a farm under false pretenses and take video or sound recordings.