Federal agencies set to get more powers to enforce US marijuana laws
US attorney general Jeff Sessions is to rescind a policy forbidding federal intervention in states where marijuana is legal, sources said.
The move will leave it to US lawyers where the substance's use is legal to decide whether to aggressively enforce federal marijuana law.
An official announcement of the new policy is expected.
The move likely will add to confusion about whether it is permitted to grow, buy or use marijuana in states where it is legal, since long-standing federal law prohibits it.
The decision comes days after California began selling recreational marijuana.
Mr Sessions compares marijuana to heroin and blames it for rises in violence.