A registry might keep criminals and the mentally ill from "legally" owning guns, or at least point out those who've broken the law. Unfortunately, it wouldn't keep them from getting a gun through illegal means (theft, black market, ID fraud).
A registry wouldn't prevent mentally ill from getting guns...that's the job of background checks.
...and background checks won't do a complete job of identifying that unless HIPAA is revised.
Currently, if a person is bipolar, but has never been institutionalized and never committed a crime, they can pass the background check with no issues.
When, in fact, if HIPAA privacy regulations were loosened up a bit, it might at least allow for the raising of red flags. Not saying that bipolar people don't have a right to defend themselves, and some bipolar is mild enough that the person wouldn't be a risk...however, in some of the more severe cases, those people shouldn't own firearms. However, that won't get prevented until the privacy laws are re-written.
As it currently stands under HIPAA, a person could be severely manic depressive, and as long as they've never been institutionalized, HIPAA says that information is strictly private between them and their doctor and nobody else's business...
Keeping in mind that it was folks on the left that pushed for such strict privacy laws pertaining to HIPAA, I feel they have no right to complain or point fingers at the other side of the fence when a mentally ill person gets a firearm and goes on a rampage.
Now, from a personal perspective, I agree with OldWiseGuy
"If we calculate the probable cost in dollars and freedom lost needed to prevent a few nutcases from possessing guns we would realize the futility of it. Some losses are unavoidable."
However, if the position we, as a nation, are going to take is "We can prevent gun deaths with background checks", then I just ask for a little consistency from the left on this one.
"We need to stop mentally ill from getting their hands on guns"
...doesn't jive with...
"It's none of your business if a person (or someone in their household) has a mental illness"
It comes down to a choice, either stopping mentally ill from getting firearms is the top priority...or privacy is the top priority.
Pick one...
If you want to guarantee that background checks screen out people that have a potentially dangerous illness (or screen out a person with someone in their household that has one), you're going to have to sacrifice a little privacy.
If you want to guarantee privacy, you're doing to have to accept that we run the risk of a potentially unstable person passing the background check.
Now, I'm not saying I agree or disagree with either of these approaches here...for the sake of debate, I'm just asking that people make a choice.