“It is still a federal offense to possess marijuana, and federal law controls for immigration.” – ILRC
From the ILRC:
“What to do: Legal Self-Defense for Noncitizens
• Don’t use marijuana until you are a U.S. citizen. Don’t work in a marijuana shop.
• If you have a real medical need and there is no good substitute for medical marijuana, get legal counsel.
• Never leave the house carrying marijuana, a medical marijuana card, paraphernalia (like a pipe), or accessories like marijuana T-shirts or stickers. Don’t have photos or text about you and marijuana on your phone, Facebook, or anywhere else.
• Most important, never admit to any immigration or border official that you ever have used or possessed marijuana, unless you have expert legal advice that this is OK. If a federal official asks you about marijuana, say that you don’t want to talk to them and you want to speak to a lawyer. You have the right to remain silent. Stay strong – once you admit it, you can’t take it back. If you did admit this to a federal officer, get legal help quickly.”