Story highlights The decision had been closely watched since Sessions was sworn in

The practical implications of the new guidance are uncertain

The industry reacted with immediate alarm

(CNN) Attorney General Jeff Sessions on Thursday rescinded a trio of memos from the Obama administration that had adopted a policy of non-interference with marijuana-friendly state laws.

The move essentially shifts federal policy from the hands-off approach adopted under the previous administration to unleashing federal prosecutors across the country to decide individually how to prioritize resources to crack down on pot possession, distribution and cultivation of the drug in states where it is legal.

While many states have decriminalized or legalized marijuana use, the drug is still illegal under federal law, creating a conflict between federal and state law. Thursday's announcement is a major decision for an attorney general who has regularly decried marijuana use as dangerous.

In a written statement Thursday, Sessions called the shift a "return to the rule of law" but he did not go as far as some advocates had feared he might, stopping short of explicitly directing more prosecutions, resources or other efforts to take down the industry as a whole.

"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," Sessions said in a memo to all federal prosecutors. "These principles require federal prosecutors deciding which cases to prosecute to weigh all relevant considerations of the crime, the deterrent effect of criminal prosecution, and the cumulative impact of particular crimes on the community."

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