Definition of "committed"
Clayton Cramer has an interesting posting relating to an article in Journ. of the American Academy of Psychiatry Law. The gist of it is that the cases are clear that an involuntary committment can create prohibited status under GCA 68, they're all over the place beyond that point. Some say that a temporary emergency committment that doesn't lead to a formal committment proceeding is no bar to gun ownership. Others say that a procedure where the committment order is issued by two physicians, without judicial findings, is enough.
Going to the article he cites, indeed it is a mess, beyond the principle that if a committment is for observation, without subsequent finding that the person is indeed insane, he's probably in the clear.
At the level of state law, it's even worse. In four states, voluntary committment, or diagnosis without committment, can be a bar. In California, just being given a 72 hour committment for observation is a bar, altho it ends after five years. Four states have no bar based on psychiatric findings at all.