Less than five percent of crimes in the U.S. involve people with mental illnesses, and they’re actually less likely than those not diagnosed with mental illness to commit a gun-related offense. So although this form of gun regulation does sound good on the surface, it will only rob already-disadvantaged people of their constitutional rights to very little effect.
Even the liberal American Civil Liberties Union often opposes gun control measures that restrict which type of person purchases firearms. Generally speaking, they deem “laws that regulate or restrict particular types of guns or ammunition, regardless of the purchaser” as permissible, raising few legal red flags, but regulations which “restrict categories of purchasers” like immigrants or the mentally ill are suspect, because they’re based on flimsy evidence, and raise both due process and equal protection concerns.
This makes sense: Imagine putting people suspected of erratic behavior, due to mental illness, on no-buy lists, similar to no-fly lists. Far too many innocent people could be swept up in such a witch hunt, and it’s inevitable that some of these choices would be made based on stereotypes and faulty analysis, as with no-fly lists. Not every mental illness is the same, and not every person who suffers is likely to be violent (in fact, quite few are). Standards like the one proposed in AB 1968 are too broad, with potential to do harm to large swaths of the population.