While some citizens may have won the right to use medical marijuana, winning one right may come at the expense of another.

In a letter to firearms dealers across the country, federal authorities are being clear that firearms should not be sold to medical marijuana users.

The Alcohol, Tobacco, and Firearms agency (ATF) is sending a letter to gun dealers warning them it is illegal to sell the weapons to people who admit smoking medical marijuana and have a medical marijuana card -- something the card holders are unimpressed about.

"I'm a medical marijuana patient and I own a gun," says Arizona resident Sunny Singh, who fears his right to carry a firearm will be affected.

"A lot of these people who really need medical marijuana as a medicine shouldn't be targeted or have their rights taken away."

Even though voters made medical marijuana legal in Arizona at the end of last year, the federal government says the drug is still illegal.

Federal laws say dealers cannot sell guns to people who use illegal drugs or are addicted to drugs.

But the law doesn't specify whether or not gun dealers are required to ask customers if they have a medical marijuana card. There is confusion about the consequences if a card holder buys a gun and simply does not tell the dealer.

"Clarification would be nice, let people know what the rules are so they can understand if they're doing the right or wrong thing," Singh says.

Newscore contributed to this report.

To read more on this story see the myFOXphoenix.com story here.