Pro-gun lobbyists and some organizations that advocate on behalf of mentally ill people are finding common purpose, undermining efforts to keep guns out of the hands of people who should not have them.

Though this odd alliance may be unwitting, it is evident in Washington where the Obama administration has tried without success to expand background checks to block more people suffering from mental illness from possessing guns. It also is at work in Sacramento, where advocates are fighting an expansion of California’s state-only list of persons prohibited from owning guns.

As it has so many times before, the question of mental illness and guns arose last week when Aaron Alexis, a man who reportedly was delusional, massacred 12 people at the Navy Yard in Washington, D.C., before he died.

President Barack Obama reacted to the Sandy Hook Elementary School slaughter in December by calling for tighter background checks to keep guns out of the hands of unstable people.

While the legislation failed, the U.S. Department of Health and Human Services proposed easing privacy laws so that states could more readily feed the names of people judged mentally ill into the National Instant Criminal Background Check System, the federal database of people who are barred from having guns.

The concept seems so simple. People deemed to be a danger to themselves or others shouldn’t have guns. But as so often happens in Washington, ideology trumps common sense.

Reading through 2,052 public comments on the proposed changes, I found a few that were supportive. Far more were like the one by Gun Owners of America, an organization created by former California state Sen. H.L. Richardson:

“The day these regulations become law, lawyers will be lining up to sue deep-pocket psychiatrists for every case where they failed to turn in a patient to NICS – if the patient subsequently engages in a horrific act.”

And then there was the National Alliance on Mental Illness, among the most prominent advocates for mentally ill people. The group said it “shares the goal of reducing gun violence.”

“At the same time, NAMI strongly advocates that people should not be treated differently with respect to firearms regulations based on stereotypical assumptions about mental illness and its relationship to violence,” the advocacy group said.

The proposal is pending.

In April, the Congressional Research Service issued a report detailing the holes in the system of collecting information about individuals with a history of mental illness, to little effect.

The federal database includes more than 1.8 million people who have been “adjudicated” as being mentally ill. State laws are a mishmash. People barred from owning guns in one state can cross state lines and buy weapons of their choice.

The report said only 12 states regularly supply the data, California included, while 13 states have no laws governing the collection or reporting of mental health records for use in firearm purchaser background checks.

In Sacramento, Disability Rights California, a legal aid group that advocates on behalf of people with severe mental illness, and receives state and federal funding, is on the same side as the National Rifle Association as both groups fight the expansion of California’s list of individuals who would be denied the right under state law to possess firearms.

Senate Bill 755 pending before Gov. Jerry Brown would ban gun possession by individuals who have been convicted of multiple alcohol-related offenses. Severely mentally ill people would have to give up their guns if judges direct that they undergo intensive outpatient therapy.

“Mental illness and guns don’t mix, just as alcohol and drug use and guns don’t mix,” said Sen. Lois Wolk, D-Davis, the bill’s author.

Wolk’s common sense aside, Disability Rights invoked Second Amendment rights in a letter to legislators and urged Brown to veto the measure, saying it “would likely raise equal protection arguments.”

No doubt, some group will sue claiming an equal protection violation. I would hope that the judges who rule on the case place the protection of society over the loss of one person’s gun rights.

At the memorial for the 12 people shot to death at the Navy Yard, Obama had all but given up trying to get serious gun control legislation through Congress and lamented the “creeping resignation” that mass shootings have become the norm.

“Clearly we care. Our hearts are broken again. The question is do we care enough?” the president asked.

Obama’s question is worth considering. Certainly, stigma of people with severe mental illness is real. Without a doubt, society has an interest in making sure they receive humane care. Courts have ruled that the Second Amendment gives people the right to have guns. But that right should not be absolute for people who through no fault of their own are unstable.