American Attorney General Jeff Sessions has cancelled a federal policy that let American states legalize marijuana. The move came just days after California, the country’s largest state, began permitting recreational use of the drug. President Donald Trump’s top law enforcement official announced the change Thursday. Instead of the earlier hands-off policy, Sessions will let federal lawyers in states where marijuana is already legal decide how aggressively to enforce federal law. In a memo, Sessions asked federal lawyers to consider the seriousness of the crime and its impact in deciding which marijuana activities to prosecute under these laws. The move by Sessions is likely to create questions in states where it is legal to buy, use and grow marijuana.