Politically, Schumer's idea has by far the best prospect of happening of any of the gun control proposals that have recently been floated. Since it involves an administrative determination and action, Congress is not involved. And the selling point that the Arizona shooter could have been stopped if the military had reported his drug use and disqualification to NICS will have great appeal in many circles.
Legally, I see substantial problems for Schumer's proposal. Applying it to past drug use would probably not stand up in court. Applying it to recent or current drug use might well survive a court challenge. That would lead to another issue - once a name goes into NICS, it is extremely hard to remove.
Legally, I see substantial problems for Schumer's proposal. Applying it to past drug use would probably not stand up in court. Applying it to recent or current drug use might well survive a court challenge. That would lead to another issue - once a name goes into NICS, it is extremely hard to remove.