How easy is it to buy a gun in Texas?
President Barack Obama has said he is determined to curb gun violence in the United States following a series of massacres, some of them by people with mental health problems.
But a BBC investigation for Panorama has found that in many parts of America people can legally buy guns despite suffering from severe mental illness.
Panorama reporter Hilary Andersson goes undercover at a gun show in Texas and finds that it is possible to buy an AR15 assault rifle without any background checks.
The charity Mental Health America said: "People with mental health conditions are much more likely to be victims of violence than perpetrators and equating mental illness with violence is false."
Watch Panorama: America's Gun Addiction on Monday 11 March, 2030 GMT, BBC One, and for seven days afterwards on the BBC iPlayer.