Apparently the scum who murdered 9 people in San Jose CA was bipolar and possessed a number of firearms! If you are familiar with bipolar people you know that they should never be allowed access to firearms because they frequently are insanely violent.
I don't think its that simple. I have two relatives who are bi-polar and neither has exhibited any violent behavior during their crazy spells. I'd be more concerned regarding them having guns around that they would commit suicide.
This is a very difficult thing and I don't think that there is going to be a good answer. Some people are crazy and should not be allowed to own guns. Who gets to define what crazy is and how crazy you can be before your guns are grabbed, is going to be hugely problematic and someone's rights are gonna get wrongly infringed without doubt.
On the other hand, with a lot of these shooters, in the aftermath, people will say "well everyone knew he was crazy and always has been".
