Anyone who is not a U.S. citizen should use extreme caution before partaking in California’s newest legal recreational activity because it could have serious immigration consequences, according to attorneys.

Marijuana is still illegal at the federal level, and it doesn’t take a conviction for using it to affect a non-citizen’s future. If a port official finds out that someone entering the U.S. with a visa has used the drug, the official can ban the person from the country for life.

[related_articles location=”left” show_article_date=”false” article_type=”automatic-primary-section” curated_ids=””]That means if a green card holder is selected for a search after traveling outside the U.S. for vacation and officials find a receipt from a dispensary, cellphone or social media photos at a pot shop, or anything else to suggest the immigrant has consumed marijuana, that person can be kicked out of the U.S. forever.

Some immigration attorneys in San Diego emailed warnings to their clients after the drug became legal at the state level for recreational use on Jan. 1.

“One of the grounds for inadmissibility is whether you are a drug abuser or drug addict,” immigration attorney Andrew Nietor explained. “That is interpreted fairly conservatively. Any admission of prior drug use will often lead to a presumption that the person has a controlled substance problem.”

Nietor said that clients are often surprised when he tells them what can happen if they smoke pot.

“One thing the law should always do is provide clear guidelines for people so they know what is going to violate the law and what is not going to violate the law,” Nietor said. “The big problem right now is that there is so much confusion that someone could engage in an activity that involves them getting a license from the state, and the federal government could say that activity is unlawful and result in permanent exile from the U.S.”

An official from Customs and Border Protection said the agency doesn’t track how many people are turned away at the border for drug use.

Non-citizens should also avoid working at dispensaries or growing marijuana, attorneys said, since that’s still considered drug trafficking under federal law.

Stories about non-citizens being banned from the U.S. over marijuana surfaced after other states legalized the drug, and some California residents had problems once it became legal for medical use.

Check out our updated map showing shops licensed to sell recreational cannabis in California.

Allan Lolly, an immigration attorney, said he ran into an issue involving a pot plant when one of his clients was being interviewed for a green card. She was here from Bulgaria on a student visa, and she had married a U.S. citizen.

When the officer asked the couple about their home, the husband mentioned that he grew a small marijuana plant in one of the rooms.

“Both of us were surprised,” Lolly recalled, referring to himself and the officer. “We paused for a moment, and everybody was quiet. I said, ‘Can I talk to my client privately?’”

The officer allowed them to meet, and after the wife explained that she wasn’t in any way connected to the plant and actually disapproved of it, the officer authorized her green card.

Lolly has also seen clients applying for visas, particularly from the United Kingdom or Jamaica, who are denied over marijuana use, he said.

More than 1,300 immigrants were unable to get visas because of drug use in fiscal 2016, according to a report from the State Department. More than 3,000 people were unable to get temporary visas for the same reasons.

Marijuana use can also affect someone’s ability to become a U.S. citizen.

Any offense other than simple possession of less than 30 grams of marijuana is a permanent bar from the U.S., Lolly said. Simple possession also results in a ban, but a non-citizen can apply for a waiver.

Green card holders have a right to a court hearing before losing their green card for pot use, according to immigration attorney Ginger Jacobs, but people traveling on temporary visas, like students and tourists, can be turned around at the border with no recourse.

She had a client who was a legal permanent resident and had a medical marijuana card. He periodically drove to Los Angeles with weed in the car to have it turned into butter.

He was stopped and charged with possession with intent to distribute, and the charge was reduced to simple possession after he explained the situation.

Later, when he left the U.S. on a trip and came back, he was detained and ended up in court fighting to keep his green card. Jacobs was able to help him keep it.

Check out our package of reviews of cannabis products fore pain relief.

“If he’d been a citizen, there wouldn’t have been a complication,” Jacobs said. “He wouldn’t have had to deal with proceedings that were expensive and stressful.”

Dispensaries scanning ID cards and tracking purchases especially concerned her.

“I would highly encourage immigrants to be very, very wary of making a purchase until they’ve naturalized,” Jacobs said.

She also cautioned non-citizens not to get caught with marijuana at national parks or on other federal land. Officers can and will charge people under federal law there, and a controlled substance conviction can lead to deportation even for green card holders.

If an immigrant does get caught, Jacobs said, he or she should not leave the U.S. and should talk to an attorney.

To subscribe to The Cannifornian’s email newsletter, click here.