SALT LAKE CITY – Conservative lawmakers in Utah have fired another salvo in their longtime campaign against online porn with a new requirement that all cellphones and tablets sold in the state automatically block pornography in a plan that critics call a significant intrusion on free speech.

Supporters and critics alike are now waiting to find out if new Gov. Spencer Cox, a Republican, will sign or veto a proposal that the GOP-controlled Legislature passed this month.

Cox hasn’t indicated publicly which way he’s leaning. His spokeswoman, Jennifer Napier-Pearce, said only in an email that Cox “will carefully consider this bill during the bill signing period.” He has until March 25 to decide.

Supporters argue the restriction is a critical step to help parents keep explicit content away from kids – especially as more children have their own electronic devices and have been forced to spend more time online during the pandemic.

Combating porn is a perennial issue for Utah lawmakers who have previously mandated warning labels on print and online pornography and declared porn a “public health crisis.”

Utah’s generally conservative culture means racy mainstream magazines and lingerie catalogs can be considered risqué. Leaders of the predominant Church of Jesus Christ of Latter-day Saints faith have also drawn attention to what they consider the harms of pornography.

Even if Cox signs the measure, it wouldn’t go into effect unless five other states also enacted similar laws, a provision added after manufacturers and retailers voiced concerns that it would be difficult to implement the filters for a single state.There is some precedent for other states following Utah’s example on porn – more than a dozen states advanced similar resolutions to declare porn a public-health crisis after the state became the first to do so in 2016.

If Cox signs the bill, Utah appears poised to become the first state to mandate filters on devices, according to two prominent technology experts and the bill’s sponsor, though federal internet restrictions aimed at preventing kids from accessing porn were passed in the late 1990s and later stuck down in the courts.

The National Center on Sexual Exploitation, an anti-porn group, cheered the bill, saying that while many electronic devices come with filters installed, turning them on can be challenging for parents.

“Utah has passed a critical, common sense solution to help protect vulnerable children from accessing harmful pornographic content on phones and tablets,” Executive Director Dawn Hawkins said in a statement. Adults would be able to turn off the filters if they chose.

Research has raised questions about how pornography shapes kids’ attitudes about sex, and content filters can be an important tool in keeping children from being exposed before it’s healthy, said Emily Rothman, a Boston University professor who has studied the issue.

But even more important is comprehensive sex education to counteract messages kids might get from porn, she said.

Moves to expand sex education face long odds in Utah, and this year a bill that would have required more discussion about consent in sexual encounters died at the state Legislature.

Republican Rep. Susan Pulsipher sponsored the pornography filter measure, though she acknowledged it isn’t a complete solution.

“A child that wants to find it and tries to would probably be able to still. It’s just one step in the right direction,” she said.

She contends the measure passes constitutional muster because adults can deactivate the filters, but experts said it still raises several legal concerns.

“You’ve basically got the state mandating the filtering of lawful content. That raises immediate First Amendment flags,” said Samir Jain, policy director at the Center for Democracy and Technology, a Washington, D.C.-based internet policy group.

The bill as written could apply to any device “activated” in Utah, raising the possibility that it could require location tracking to activate filters on the phones of anyone coming into the state, Jain said.

The new porn filtering plan harkens back to the attempts struck down in the 1990s, and if it does go into effect, “my guess is a device manufacturer would go into court the next day and have the law enjoined,” said David Greene, civil liberties director with the Electronic Frontier Foundation, a San Francisco-based internet civil liberties group.

The U.S. does allow for some explicit materials to be restricted from minors, but it’s a fine distinction that can require the courts to define, Greene said.

And he said no existing filters are that sophisticated: “It’s not like you put a judge in your phone,” he said.

The filters in the marketplace have also been known to block other types of content, such as nude art works, educational information and facts about sex and sexuality, said Mike Stabile, a spokesman for the Free Speech Coalition, an adult-entertainment trade group.

The American Civil Liberties Union of Utah said the bill is an overreach that imposes the same standards on everyone.

“Parental filters already exist,” said attorney Jason Groth, “and every Utah parent can decide the level of access for their children.”