Reports are that the shooter wasn’t allowed to own a gun. Pro-gun types will point to this as evidence that gun control wouldn’t have made a difference. Criminals don’t follow the law, they argue. I see three possible explanations for how the shooter got his weapons. Universal background checks would have helped in at least 2 of the 3 and possibly in all 3.
1. A law-abiding gun owner sold him the gun not knowing he was disqualified. If background checks through a FFL were mandatory for all firearms transactions, a responsible gun owner would have found out about his disqualification and not sold it to him.
2. A criminal gun owner sold him the gun despite knowing he was disqualified. If background checks through a FFL were mandatory for all firearm transactions, law enforcement would be able to track the gun to figure out who allowed the gun to enter into the black market. Here is how that would work: Police send the serial number to the gun manufacturer. The manufacturer says “we sent the weapon to FFL1.” The police go to FFL1. They look in the records they are already required to keep and say, “We sold the weapon to Person1.” The police to go Person1 who says “I sold the gun. FFL2 did the background check.” The police go to FFL2 who looks in his records. “Person1 sold the gun to Person2.” The police go to Person2. Person2 says, “I sold the gun but I didn’t have an FFL do a background check on the buyer.” Police arrest and convict Person2.
3. The gun was stolen/borrowed. Here the chain of ownership may be irrevocably broken. However, the ability to trace the gun to the point of theft would still be useful. If multiple crime guns can be traced to the same person claiming the guns were stolen, it won’t take police long to realize the “victim” is actually a gun runner / straw purchaser for criminals.