What failed in this instance is the firearm owner's lack of properly securing his/her weapon. A simple trigger lock or gun safe/cabinet would of prevented them from being taken. Hell....mine are in a biometric safe beside my bed. Only myself & my woman can get into them unless someone clones our fingerprints. It's not the law that failed, its the home the weapons came from.
The law as it stands is clearly not enough then. Surely there need to be regular unadvertised inspections of houses to make sure owners are securing their weapons properly, and have all the weapons they say they do and haven't lent them to someone or sold some of them?