Associated Press

WASHINGTON — The Trump administration threw the burgeoning movement to legalize marijuana into uncertainty Thursday as it lifted an Obama-era policy that kept federal authorities from cracking down on the pot trade in states where the drug is legal. Attorney General Jeff Sessions will now leave it up to federal prosecutors to decide what to do when state rules collide with federal drug law.

Sessions' action, just three days after a legalization law went into effect in California, threatened the future of the young industry, created confusion in states where the drug is legal and outraged both marijuana advocates and some members of Congress, including Sessions' fellow Republicans. Many conservatives are wary of what they see as federal intrusion in areas they believe must be left to the states.

It is not clear how the change might affect states where marijuana is legal for medical purposes, including Florida. A congressional amendment blocks the Justice Department from interfering with medical marijuana programs in states where it is allowed. Justice officials said they would follow the law, but would not preclude the possibility of medical marijuana-related prosecutions.

Officials wouldn't say whether federal prosecutors would target marijuana shops and legal growers, nor would they speculate on whether pot prosecutions would increase.

"I wouldn't get overly concerned that a state prosecutor is going to come after cancer patients by any means," said state Sen. Jeff Brandes, R-St. Petersburg, who has long been a leader on medical marijuana policy in the state. "But we need to monitor this closely."

While Florida's fledgling medical marijuana market, with all its stops and starts, may not be a high-profile target, Sessions' announcement could have a chilling effect on the growth of the industry in the Sunshine State, said Ben Pollara, executive director of marijuana advocacy organization Florida for Care and one of the authors of the medical marijuana amendment.

"This is happening at a time when real institutional money and actors are starting to play in this space, and now those guys are going to go right back to the sidelines," Pollara said. "Florida's industry is in its infancy, but the players are giants, big companies with a lot of money. If investors start backing out, that will make it more difficult for these companies to deliver to the thousands of patients who've registered for this across the state."

Republican Sen. Cory Gardner, who represents Colorado, one of eight states that have legalized marijuana for recreational use, said the change contradicts a pledge Sessions made to him before being confirmed as attorney general. Gardner promised to push legislation to protect marijuana sales, saying he was prepared "to take all steps necessary" to fight the change, including holding up the confirmation of Justice Department nominees. Another Republican senator, Lisa Murkowski of Alaska, called the announcement "disruptive" and "regrettable."

Colorado's U.S. attorney, Bob Troyer, said his office won't change its approach to prosecution, despite Sessions' guidance. Prosecutors there have always focused on marijuana crimes that "create the greatest safety threats" and will continue to be guided by that, Troyer said.

The largely hands-off approach to marijuana enforcement set forth by Barack Obama's Justice Department allowed the pot business to flourish into a sophisticated, multimillion-dollar industry that helps fund some state government programs. What happens now is in doubt.

"In deciding which marijuana activities to prosecute under these laws with the Department's finite resources, prosecutors should follow the well-established principles that govern all federal prosecutions," considering the seriousness of a crime and its impact on the community, Sessions told prosecutors in a one-page memo.

While Sessions, a longtime marijuana foe, has been carrying out a Justice Department agenda that follows Trump's top priorities on such issues as immigration and opioids, this change reflects his own concerns. He railed against marijuana as an Alabama senator and has assailed it as comparable to heroin.

Trump, as a candidate, said pot should be left up to the states, but his personal views on marijuana remain largely unknown.

Officials said Thursday's action might not be the only step toward greater marijuana enforcement. The department has the authority to sue states on the grounds that state laws regulating pot are unconstitutional, pre-empted by federal law.

Sessions "wants to maintain a system that has led to tremendous injustice … and that has wasted federal resources on a huge scale," said Maria McFarland Sanchez-Moreno, executive director of the Drug Policy Alliance. "If Sessions thinks that makes sense in terms of prosecutorial priorities, he is in a very bizarre ideological state, or a deeply problematic one.

Times staff writer Justine Griffin contributed to this report.