Cho was disqualified by a court in VA to possess guns and ammo. VA decided not to enter the records for that fed disqualification into the fed database. This law requires those records to be entered, so when a background check is run, those records show up.
Actually it wasn't that specific. He was adjudicated, by a "Special Court" judge (no jury) as : "presents an imminent danger to himself as a result of mental illness."
But he was specifically not adjudicated as:"Presents an imminent danger to others as a result of mental illness."
It sounds from this ABC News article (from where the quotes above came), as if the Special Court is pretty much a rubber stamp for the findings of the shrinks.
What's to stop a similar "Special Court" from reviewing the records of Veterans diagnosed as having PTSD and issuing similar findings? (Only maybe adding "and others" to the "danger to self")