It's not the entire answer to the problem of gun violence in America. It's not even the single most important answer. But it's a part of the elusive solution -- and we're not doing a very good job of putting it into practice, even though we have some of the tools.

In California, individuals with certain mental health problems can be barred from owning or possessing guns. That hasn't happened nearly often enough, according to a Bureau of State Audits report that finds 34 of the state's superior courts failed to file firearm prohibition reports to the justice department's mental health unit from 2010 through 2012. The main reason? They didn't know they had to.

Laws on this subject might have been easy to miss in years past, but no longer. This year several bills toughening such rules have been enacted, including one just this month. Assembly Bill 1131 increases the length of time a person is banned from possessing firearms after making a threat against a licensed psychotherapist. Once six months, now it's five years.

Of the county superior courts surveyed (Kern was not among them) only Riverside and Contra Costa counties were aware of the relevant laws -- and even they had incomplete or no record of how many such determinations they reported. As best the bureau could discern, 2,300 cases that should have been flagged during 2010-2012 were not reported.

In view of the fact that many perpetrators of mass shootings have had documented mental health issues, it is logical that governments should restrict those who have been diagnosed. Laws are in place to authorize such restrictions; California courts just need to act on them. Tighter scrutiny won't make a reportable dent in the frequency of these gun tragedies, because we can't tabulate what never had the opportunity to occur.

But we've got to do what makes sense.