Pennsylvania, Alaska, Nevada and Hawaii are the first states to require gun confiscation from medical marijuana users. They are easily targeted because their personal information was given to their home state in exchange for a  medical marijuana user card.

According to U.S. District Judge Jed Saul Rakoff, pictured above, "It is beyond dispute that illegal drug users, including marijuana users, are likely … to experience altered or impaired mental states that affect their judgment and that can lead to irrational or unpredictable behavior" which promotes gun violence.

Judge Rakoff also said that the federal government had a "substantial interest" in preventing gun violence by seeking to prevent drug users from possessing firearms. 

His ruling in Wilson versus Lynch was written on August 31, 2016. It is linked below:

http://cdn.ca9.uscourts.gov/datastore/opinions/2016/08/31/14-15700.pdf

States like Pennsylvania, Hawaii, Nevada, and Alaska have taken Rakoff's ruling a step farther. These states have started programs to confiscate guns from medical marijuana within the last month. Rakoff's ruling was only intended to stop marijuana users from purchasing guns.

The position of the U.S. Justice Department's Bureau of Tobacco, Alcohol, and Firearms (ATF) has been unchanged since June 21, 2011. That position, according to Arthur Herbert, Assistant Director of Enforcement Programs and Services at the U.S. Justice Department's Bureau of Alcohol, Tobacco, and Firearms (ATF), is "marijuana is a controlled substance" and "any marijuana user is prohibited by federal law from owning a firearm". His "Open Letter to All Firearms Dealers" is linked below:

https://www.atf.gov/file/60211/download

Herbert retired in 2014. The person in charge of policy now is Ronald Turk. He is pictured in the last frame below.