Colorado regulators will not enforce — at least initially — a new law requiring marijuana-themed magazines to be kept behind the counter at stores that sell them.

But lawyers for the magazines and for booksellers still want a federal judge to rule the law unconstitutional, arguing that the state could later change its mind.

“There is a fear that what the Department of Revenue giveth, the Department of Revenue may take away,” attorney David Lane said at a hearing Thursday on two lawsuits that challenge the law.

The legislature adopted the new law earlier this year as part of a major bill for regulating recreational marijuana sales. The law says marijuana magazines must be sold behind the counter in stores that people under 21 are allowed to visit — such as a bookstore or newsstand.

The law has prompted two lawsuits in federal court challenging its constitutionality, one by three marijuana-themed publications and another by booksellers and backed by the American Civil Liberties Union. The lawsuits say the law violates free speech by restricting distribution of the magazines based on their content.

In an emergency rule issued Wednesday, regulators with the state Marijuana Enforcement Division concluded the law is unconstitutional.

“[S]uch a requirement would violate the United States Constitution, the Colorado Constitution” and state law, the rule states.

The state attorney general’s office signed off on the emergency rule.

“We support the laudable goal of keeping retail marijuana out of the hands of those under 21, but that has to be consistent with the Constitution,” attorney general’s spokeswoman Carolyn Tyler said.

Tyler said the emergency rule is only temporary and could be changed during a permanent rulemaking process scheduled to start next month. She said stores that sell marijuana magazines can still voluntarily keep the magazines behind the counter.

At the court hearing, Lane said prosecutors may still try to use the underlying law to charge magazine-sellers who don’t keep pot publications behind the counter with misdemeanors, despite the new emergency rule.

Deputy Attorney General David Blake, arguing for the state, said the emergency rule means the law isn’t in effect.

“There is no district attorney who has a law to enforce,” Blake said.

Senior U.S. District Court Judge Richard Matsch agreed he didn’t need to decide the case immediately.

“I don’t think we have the hot breath of a district attorney on any of the plaintiffs,” he said.

But Matsch sharply rejected the state’s contention that the emergency rule means the lawsuits should be dismissed as moot. Matsch said the state would not be allowed to file a motion to dismiss, and instead ordered the state to respond to the lawsuit formally by the end of the month.

John Ingold: 303-954-1068, jingold@denverpost.com or twitter.com/john_ingold