Use, possession, sale and other activities relating to marijuana/cannabis are legal in many states in the United States and in other places worldwide. However, all marijuana activities (with very limited scientific research exceptions) are illegal under US federal law and in turn under US immigration law.
Non-US citizens using marijuana and/or involved in legal cannabis activities throughout the US put themselves at risk of being found inadmissible to the US (that is, unable to enter the US), removable from the US (that is, deportable), and/or ineligible for US citizenship. Some immigration issues arise only when a person has a criminal conviction for marijuana related crimes; other immigration arise merely when a person admits to crimes related to marijuana use. Other immigration issues arise merely when a US immigration officer has “reason to believe” that a person is involved in marijuana trafficking (and trafficking can be as simple as a state law relating to intent to distribute).
In USCIS in Seattle and Denver, USCIS officers are asking enough questions in immigration interviews to elicit “admissions” to marijuana crimes, rendering immigrant ineligible for certain immigration benefits and in some cases, deportable.
AILA issued the Practice Pointer below discussing this issue.
If you use or have used marijuana in the past and are NOT a US-citizen, you should speak with an experienced immigration attorney about the potential consequences on your current or future immigration status.