On its face, Maine’s “yellow flag” law, enacted in 2019, could have made a crucial difference in this case. It authorizes police, after taking someone into “protective custody” based on probable cause to believe he is “mentally ill” and poses a threat to himself or others, to ask a “medical practitioner” for an assessment of whether the detainee “presents a likelihood of foreseeable harm.” …

Gun control activists complained that Maine’s “yellow flag” law is harder to use than the “red flag” laws that 21 states have enacted, which have fewer and weaker procedural protections. That criticism seems doubly misguided.

First, this looks like a situation where Maine’s law could have been used but for some reason was not. Second, the state’s requirements are aimed at minimizing the number of people who lose their Second Amendment rights for no good reason.

Weaker protections for respondents might make effective intervention more likely. Or they might not.

Despite what in retrospect looks like clear warning signs, New York’s “red flag” law did not prevent the massacre that killed 10 people at a Buffalo supermarket in 2022. Nor did California’s “red flag” law prevent two mass shootings that killed 18 people in that state last January.

One thing is clear: Casting a wider net inevitably means that more people will be deprived of their constitutional rights even when they do not actually pose a threat to public safety. That is true not only of “red flag” laws but also of the federal ban on gun possession by people who have been involuntarily committed to psychiatric institutions, which applies no matter how long ago that happened and regardless of whether they were ever deemed a threat to others.

— Jacob Sullum in Don’t Blame the Maine Shootings on ‘Woefully Weak’ Gun Laws