Richard Martinez is demanding "immediate action" from Congress in response to the murder of his son and five other people in Isla Vista, California, on Friday night. "I don't care about your sympathy," he tells The Washington Post, referring to the legislators who have called him to offer condolences. "I don't give a shit that you feel sorry for me. Get to work and do something." Yet Martinez candidly admits he does not know what that something should be. "I understand this is a complicated problem," he says. "There's no playbook for this. We don't know what we are doing. I just know I have to keep fighting until something changes."

Today a New York Times editorial takes a stab at describing that something, calling for "a better definition of how severe a mental illness needs to be before it prevents someone from possessing a gun." Under the Gun Control Act of 1968, anyone who has been involuntarily committed to a mental institution is prohibited from owning a firearm. One could argue that such a rule is too broad, especially since it covers people viewed as threats to themselves as well as people viewed as threats to others. Should everyone who is forcibly treated because he is thought to be suicidal forever lose his Second Amendment rights?

The Times has no such qualms. To the contrary, it views the current standard as a "high bar" and worries that it "misses thousands of people." In truth, it misses tens of millions, since survey data indicate that half the population qualifies for a psychiatric diagnosis at some point. Hence "a better definition of how severe a mental illness needs to be before it prevents someone from possessing a gun" could have sweeping implications for Americans' constitutional rights.

California already has expanded that definition, prohibiting gun ownership by anyone who has been subject to a 72-hour psychiatric hold aimed at determining whether he is a threat to himself or others within the previous five years. In other words, merely being suspected of posing a threat to yourself or others is enough for you to lose your Second Amendment rights in California. But it turns out that the Isla Vista shooter, Elliot Rodger, not only had never been involuntarily committed; he had never been involuntarily evaluated either.

The closest Rodger came to a 72-hour hold seems to have been in April, when Santa Barbara County sheriff's deputies visited him at his apartment after his mother, alarmed by his dark and brooding YouTube videos, reported that he might be suicidal. The deputies, finding Rodger to be calm and polite, did not see any evidence that he was a threat to himself or others. He reassured them that he had been going through a difficult time but was not about to kill himself, and they believed him. They did not have enough evidence to confine him for a 72-hour evaluation, which in California requires "probable cause to believe that the person is, as a result of mental disorder, a danger to others, or to himself or herself, or gravely disabled."

The Times suggests that "parents or other relatives should be allowed to petition a court for a restraining order prohibiting gun ownership by those who pose a credible risk of harm to themselves or others." Even assuming that Rodger's parents, who did not know that he owned guns, would have sought such an order, it is doubtful that they could have presented "credible" evidence to back up their request, given the absence of probable cause. Until last Friday, they had no inkling of their son's homicidal plans. They knew he was socially awkward, lonely, and depressed, but many people fit that description, and almost none of them become mass murderers. Loosening the standards for psychiatric holds, involuntary treatment, or loss of Second Amendment rights would strip many harmless people of their liberty, with no guarantee of preventing even a single violent crime.

The Times also reiterates its support for a "universal background check system." Yet every gun buyer in California has to be cleared by the state Department of Justice, a requirement that did not stop Rodger because, like the vast majority of mass shooters, he did not have a disqualifying criminal or psychiatric record. A background check is only as good as the criteria for exclusion. Since there is no reliable way to identify mass murderers before they strike, we are left with criteria that are both too broad and too narrow.

The Times suggests a few more. You should not be allowed to buy a gun, it says, if you "have been convicted of a violent misdemeanor, subject to a domestic violence restraining order, convicted of drunken driving two or more times in five years, or convicted of two misdemeanors involving a controlled substance in five years." Before adding to the exclusion criteria, shouldn't we ask whether the current ones make sense? As the law stands, any felony conviction—even for a nonviolent offense that might not even involve a victim, let alone violence—results in the permanent loss of Second Amendment rights. If you are in the country without permission, you have no right to armed self-defense. Likewise if you smoke pot or use a relative's prescription painkillers. These rules have very little to do with public safety.

And none of these policies, lest we forget, has anything to do with Elliot Rodger, whose crimes provoked this whole discussion. "Would these measures have prevented Elliot Rodger's rampage?" the Times asks. "Possibly not. With so many guns in this society, no law will ever prevent all gun violence, but that should not stymie attempts to reduce it."

You know what should stymie attempts to reduce gun violence? The likelihood that they will fail, combined with the certainty that they will deprive innocent people of freedom.