Traditionally, U.S. federal law comes down hard on any sort of drug use. Because immigration falls under federal law, marijuana use can affect visa applicants who live abroad or who are already present in the U.S. So what does that mean for a visa applicant who's coming from a country—or who lives in a U.S. state—with more permissive laws?
Let's take a reasonably likely scenario: You lived in Amsterdam for a while and smoked marijuana there on a few occasions. This wasn't against the law in that country. Could you nevertheless be denied entry into the United States? It's possible you could be found inadmissible to the U.S. in a situation like this, but not likely.
Another common scenario: You are currently in the U.S. on a temporary visa, and want to apply for a different type of visa (change your immigration status). You live in California, which has legalized recreational marijuana. Could your visa be denied on that basis? Once again, it's possible you could be found inadmissible (and therefore denied a visa), but only if there is reason to believe you've committed a federal crime.
There are two grounds of inadmissibility to worry about if you've ever used marijuana without being convicted of a crime for doing so: health grounds and criminal grounds, as discussed below.
The doctor who performs your immigration medical exam (required for all immigrant visas, but not usually for nonimmigrant or temporary visas) must determine whether you are inadmissible on the basis of having:
(These grounds of inadmissibility are found in Immigration and Nationality Act Section 212(a)(1)(A)(iii) and (iv).)
There is little risk that occasional marijuana use, standing alone, will be diagnosed as a physical or mental disorder, although if you have exhibited harmful behavior resulting from your use of marijuana, you could be at risk of being found inadmissible.
The drug abuser or addict ground of inadmissibility is not often used to find inadmissibility, because it is difficult to define and prove who is a "drug abuser" or "drug addict." However, frequent marijuana use, even if legal, puts you at risk of being found inadmissible as an abuser or addict. Certainly you should be concerned if your legal marijuana use has created some problem that requires you to admit to abuse or addiction in order to participate in a court-ordered program or therapy.
For more information on how drug addiction or other health issues can affect visa eligibility, see Can a Recovering Drug Addict Get a U.S. Visa or Green Card? and How Health Issues Can Make You Inadmissible to the U.S.
There are places in the world where use of marijuana is not a crime. If your only use of marijuana was done legally under the laws of a foreign country, you do not have to worry about criminal grounds of inadmissibility.
You might, still need to worry, however, about marijuana use in a U.S. state that has legalized or decriminalized marijuana. This is because possession of marijuana for any purpose, including personal use, remains a crime under U.S. federal law. This includes the medical marijuana prescribed by a doctor under state law. (For more information on medical marijuana use, see Can Green Card Holders Use Medical Marijuana in States Where It's Legal?)
Even if the federal government did not convict you of a marijuana offense, immigration law makes you inadmissible if you admit to past actions that would be punishable under federal law.
(This ground of inadmissibility is found in Immigration and Nationality Act Section 212(a)(2)(A)(i)(II).)
How do you "admit" to possessing marijuana, or "admit" to doing all the things that would make you guilty of possessing marijuana? It usually requires some kind of formal admission in the course of court proceedings or the immigration application process.
If, for example, you tell the doctor at your visa or adjustment of status medical exam that you've used marijuana, you might have admitted to a federal offense. If you tell the immigration officer at your interview that you used marijuana in a legal state or were prescribed a medical marijuana card, you might have admitted to a federal offense. If you work in the legal marijuana industry, this could lead to problems as well.
Often a conviction from a prior criminal case can count as an admission of an offense. Sometimes even entering into a plea bargain can count as an admission. A conviction for possessing drug paraphernalia (or an admission) could also be problematic. Needless to say, this is a complicated area of law. If you have had any prior legal issues relating to marijuana or other drugs, or if you are concerned about what to say if you are asked about drug use while in a state where it was legal, you should get the advice of an attorney.
If you admit to possessing less than 30 grams of marijuana, and admit to doing it only once, you can apply for a waiver of inadmissibility under Section 212(h) of the Immigration and Nationality Act in one of two circumstances:
Whether you will be granted this waiver is totally up to the U.S. government.
To read more about waivers of inadmissibility, see Which Crimes Can Be Waived to Get a U.S. Visa or Green Card?
Definitely get an attorney's help if you believe marijuana use could come up in your application for U.S. immigration benefits. The potential for making mistakes is high in this process, so it is wise to have an experienced professional by your side.