Why California's Strict Gun Laws Didn't Matter In San Bernardino

Syed Rizwan Farook and Tashfeen Malik walked into a San Bernardino, California, social services center on Wednesday and, armed with two assault-style rifles and two handguns, opened fire. They unleashed at least 75 rounds during the assault, killing 14 people and wounding 21. Their .223-caliber rifles had the power to penetrate ballistic vests and walls, according to the Bureau of Alcohol, Tobacco, Firearms and Explosives .

 The District of Columbia and seven states, including California, have outright bans  on assault weapons. Two other states regulate them in some fashion.

In addition to barring an array of assault weapons, California requires all gun sales to be made through a licensed dealer, and mandates background checks and a 10-day waiting period for all purchases. Those regulations apply to private gun sales -- such as those made at gun shows -- which are notoriously exempt from federally mandated background checks.

Read more on the San Bernardino shooting here .

Many states do not require background checks for those private, unlicensed sales, including transactions at guns shows, which means that a buyer might not have to say which state he or she is from. 

Among the states bordering California, Nevada and Arizona do not require background checks on private sales. 

Private gun sellers in those states are supposed to ask buyers for proof of residency, but a San Francisco Chronicle reporter found that four out of five sellers he approached at a Las Vegas gun show in January 2013 were prepared to sell him guns that were illegal in California without verifying his residency.

"What we know is that each year more and more crime guns are coming in to California from states like Nevada and Arizona that don't have laws, like expanded Brady background checks, to keep guns out of the hands of convicted felons, suspected terrorists, and other people intent on doing harm," Dan Gross, president of the Brady Campaign to Prevent Gun Violence, wrote in a statement. "The number of crime guns coming from NV and AZ, into CA has more than doubled since 2006."

Still, the vast majority of guns used to commit crimes in California originate in the state. In 2014, 15,169 of the 21,267 guns recovered by law enforcement in California, for which the state of origin was identified, came from inside the state, according to ATF . The remainder of the guns came from 14 other states. Arizona was the source of 1,184 recovered guns, the most of any outside state.

A 2008 report by Mayors Against Illegal Guns  that analyzed ATF data found a correlation between the laxness of a state’s gun laws and the likelihood that guns will be exported from that state to other places. States that require background checks on all handgun sales at gun shows have a gun export rate that is about half the national average. None of the 10 states that provided 57 percent of California's imported guns in 2007 require background checks on handgun sales at gun shows.

In a separate 2010 analysis, Mayors Against Illegal Guns found that 4,462 of guns recovered in California crimes in 2009 were imported from out of state, whereas 1,772 guns recovered in other states were found to have originated in California.

Clarification: An earlier version of this story said automatic weapons are illegal nationwide. In fact, while nearly all possession and transfer of automatic weapons by civilians has been illegal since 1986, the actions remain legal in very specific circumstances. A civilian may possess an automatic weapon that was legally registered prior to the 1986 ban, and a civilian may sell or give such a weapon to another civilian if law enforcement explicitly approves the transaction. 

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