Originally Posted by RussP
This is a bit more of a slippery slope. In order to prove negligence, you need an acceptable standard that was neglected.
Sure, a minimum standard would have to be established. It would have to be proven that the stolen guns were not protected by a reasonable method to secure them. The definition of reasonable for something as simple as a firearm security device shouldn't be so difficult. Use your imagination. A closet with a dead-bolt lock comes to mind. A gun case equipped with a padlocked cable attached to an eye bolt in the wall.
The proof that you had the device would be the existence of the device for anyone to see.