Around 100,000 convicted felons across the US still likely own a gun, despite being banned from doing so, concludes the first study of its kind, published online in Injury Prevention.
There's no nationwide programme to recover these weapons, with California the only state to do so. But such an initiative might go some way to curbing firearm violence in the US, suggest the researchers.
Relatively little attention has been paid to people who legally purchase guns but who are subsequently banned from firearm ownership because of a conviction for violent crime; or an admission to hospital for a mental health emergency; or a domestic abuse restraining order.
And there are likely to be many of them, say the researchers, because millions of people buy guns legally every year in the US and bans on ownership are common.
In California alone 5-10% of 21 to 49-year old gun owners with a history of arrest are convicted of a felony within five years of their purchase.
But as yet, California is the only US state with a large-scale enforcement programme for recovering firearms from people who have been banned from ownership.
To find out more about the number and profile of these people, the researchers drew on information entered into the Armed and Prohibited Persons System (APPS) database as of 1 February 2015.
The APPS cross references data from the California Department of Justice's archive of firearm ownership transfers with data on criminal convictions and domestic violence restraining orders. Specially trained enforcement officers then seek to recover the illegally owned weapons.
On February 1 2015, nearly 19,000 people in California owned just short of 50,000 firearms between them, despite being banned from doing so. Most of these weapons were handguns (92%).
This group was compared with 2400 randomly selected firearms owners who had not been banned from ownership.
Men predominated in both groups: 93% of those who had been banned and 85% of those who hadn't. And both groups of owners owned an average of 2.6 guns each. But banned firearm owners were more likely to be aged between 35 and 54 (60% vs 42.5%), and to be of black (11% vs 4%) and Hispanic ethnicities (27.5% vs 16%).
The average number of bans was 2 per person, but was as high as 85. Nearly half the lifelong bans (48%; 7711) had been prompted by a conviction for a felony. A 'Brady only' ban, resulting from federal, rather than state, law, applied to 29% (4623).
Bans due to violence, such as assault and battery; restraining orders; and mental health emergencies accounted for around 15% each of the total.
Most of those who illegally owned firearms lived in and around densely populated areas of the state, such as the LA and San Francisco metropolitan areas.
The researchers acknowledge that the data on firearms bans in California aren't complete, because they only date back to 1996, transactions for rifles and shotguns were only mandated in 2014, and the database doesn't include illegal purchases.
But, based on the proportion of firearm owners in California (4.2 million), and the proportion banned for felony (7711; 0.18%), the researchers estimate that 98,500 people across the US own a firearm despite being convicted felons.
"The true number of prohibited firearm owners nationwide cannot be determined with certainty using existing data, as many states do not keep records of firearm transactions and no state other than California has made these data available to researchers," they point out.
But they add: "The numerous federal prohibitions on firearm ownership, combined with the fact that no other state is engaging in comparable efforts to reduce the prevalence of armed and prohibited persons through firearm recovery, suggest there are large numbers of prohibited firearm owners across the country, particularly in states where there are higher rates of firearm ownership and fewer barriers to purchasing a firearm."
And they conclude: "The evidence supporting firearm prohibitions and interventions to reduce access to firearms among prohibited populations provides a prima facie reason to expect that recovering firearms from prohibited persons could reduce firearm violence."
Peer reviewed? Yes
Evidence type: Observational