One thing generally overlooked in the uproar over the Washington Navy Yard shooting -- and all other recent mass shootings -- is that guns are being used to shield failed liberal policies. Such policies have been implicated in most, if not all, gun massacres. As is customary when encountering failure, liberals immediately cast around looking for someone or something else to blame, in this case, guns and anything associated with them, including the NRA, the bitter clingers, and so on.

● Gun-Free Zones -- According to John Lott, Jr. every last mass killing since the 1950s has occurred in a "gun-free zone." The Navy Yard massacre is only the latest. Despite what you may have read throughout the conservative media, this is not a Clinton-era effort but was an order issued by a Defense undercrat duing the Bush 41 administration. In 2011, the order was reaffirmed by Deputy Secretary of Defense William J. Lynn III, following the Fort Hood massacre. As with similar civilian venues, this action in effect put up a sign saying, "Come on in and Kill People." Major Nidal Hasan and now Aaron Alexis have taken advantage of this offer, along with Jared Loughner, James Holmes, Adam Lanza, and Cho Seung-hui. While we can't force school boards, mall owners, or theater operators to cease putting students and customers in jeopardy, this can be accomplished quite simply as regards the military by an order from the Secretary of Defense.

● Criminal Background Checks -- It's no coincidence that this latest shooting occurred in the midst of a governmental push to outlaw criminal background checks for employment purposes. Laws of this type have been passed in California and Newark, N.J. The Obama and Holder federal government can't be far behind. As seen with "gun-free zones" the military has often been used as a stalking horse for such efforts. Have orders come down to put such a policy in effect, and was Alexis a beneficiary? We don't know, and nobody has bothered to check. The shredders in the offices of USIS, the contractor that vetted Alexis for the Navy, must have been running hot this week. (USIS also cleared Snowden. Bad sign.)

It's next to impossible to explain how this guy, with his record, was ever hired, much less given a security clearance. Alexis was cited in two previous gunplay incidents, one involving a round fired through the floor of his upstairs neighbor with whom he had exchanged words, and the other in a parking confrontation -- an aggressive act. He also committed a number of misdemeanors sufficient to separate him from the Navy in 2008, but not enough to keep him out of a critical naval headquarters as a civilian contractor.

One such incident is a misfortune. Two strongly suggests carelessness. There is no way they could have been "overlooked" during the vetting process. Somebody was ordered to ignore them.

● Affirmative action -- Both large-scale military base slayings were carried out by protected minorities. We can say without much fear of contradiction that Nidal Hassan was covered by someone -- probably many someones -- in the military hierarchy due to a desire to have a Muslim officer to show off in public. Despite his lectures praising Jihadi terrorists, his refusal to serve in theatres involving combat against "fellow Muslims," and his Jihad r' Us business cards, Hasan was shielded right up to the day he opened fire at Fort Hood. Needless to say, nobody in today's debased officer corps suffered for this.

The same process is not at all unlikely in the case of Aaron Alexis. A black Buddhist is a twofer, a catch that any affirmative action officer would boast about for the rest of his career. It's unlikely the vetting process went deeper than that. It's well known that when racial quotas are involved, other criteria are thrust aside. This practice has become life-threatening. We'll see more of it.

● Mental Health "Reforms" -- It's not easy to obtain legal control over mentally-disturbed individuals or to force them to accept treatment. Liberals like to claim that this is a legacy of Ronald Reagan, who "defunded the mental health establishment." This is an attack that mixes ignorance with ideology. In truth, the deinstitutionalization of the mentally ill was formalized in 1966 by Judge David L. Bazelon, who in a Solomonic daze discovered that the mentally ill retain all their rights despite their condition and cannot be coerced even to protect the public, which means that for all practical purposes the insane have more rights than healthy, sane individuals.

In two court cases, Bazelon (The name sounds familiar because his granddaughter Emily is a journalist specializing in legal and judicial topics for Slate, HuffPo and similar publications.) ruled that the insane could not be incarcerated against their will (Lake v. Cameron) or forced to accept any particular type of treatment (Rouse v. Cameron). This is why so many of the derelict insane are rambling homeless around urban areas rather than being under some form of care. Deprived of the alternative of incarceration, many communities allow the insane to continue acting out until blood flows. Jared Loughner, notorious in Tucson for his demented stunts, James Holmes, whose psychiatrist actually reported him to police, and Cho Seung-hui, who frightened nearly everyone he encountered at Virginia Tech, might have been safely locked away if not for Judge Bazelon's humanitarian impulses. (Bazelon was still boasting about his achievement in his memoir Questioning Authority, published in 1988, long after the horror of his decisions had become apparent.)

The same may well be true of Aaron Alexis. According to Charles Krauthammer, a trained psychiatrist, Alexis displayed every sign of schizophrenia. Following a confrontation at the Birmingham airport, Alexis called police to report that the people involved -- a vacationing black family -- had followed him to Hartford, Connecticut and were beaming microwaves at him from the adjoining suite. Shortly thereafter he was booted from Virginia naval housing following claims of laughter tormenting him from his linen closet.

The Bazelon touch is clearly visible here. Despite what was by all indications quite a loud confrontation, the Birmingham TSA did nothing. The Hartford police, presented with the classic symptoms of a psychotic breakdown, simply allowed Alexis to stumble off pursued by microwaves. It never occurred to Navy personnel in Virginia to notify Navy personnel in Washington that their new hire was as crazy as a rat in a can. The authorities were offered three chances to step in. As at Pinal College in Tucson, the University of Colorado, and Virginia Tech, they failed each time. But we got to get them AR-15s off the streets.

We could go on with this as long as we liked. It's often pointed out that without the top four American cities for homicide -- Washington, Chicago (newly crowned murder capital of the USA), Detroit, and New Orleans, the U.S. would have one of the lowest murder rates in the industrialized world. All these cities suffer from the liberal curse (while not a "liberal" city in the classic sense, New Orleans has been a Democratic stronghold since the late Devonian period, which is practically the same thing). As I demonstrated in my book Death by Liberalism, liberal "judicial reform" triggered the "Great Crime Explosion" of 1964-1994, with a death toll in the hundreds of thousands. The current plague of insane gunmen is simply a back eddy of that colossal act of hubris.

Clearly, liberalism is far more deeply implicated in the problem of gun crime, including mass shootings, than anyone is willing to admit. There's no point in sitting around grumbling about this -- it's all of piece with the liberal culture of denial inculcated since preschool. Instead, use this information. Too often 2nd Amendment advocates merely defend gun ownership. The best defense is a good offense. Make them explain why these atrocities always seem to occur in their bailiwicks, under the protection of their rules and laws, and by the hands of their protected classes -- lunatics or select social or religious oddities. That will be enough to throw them off their stride before they can erupt into their customary tantrums. They might even forget to mention the mighty AR-15.