Our good friends at Colt are feverishly working on this. However, they haven't found any electronics that can withstand the shock of firing at any levels of practical defense. Seems you cannot design something like this with gun assembly people or even mechanical engineers. You need electrical engineers with high shock electronic systems experience. High dollar folks.
Their first concern is LEO usage - to keep cops from being shot with their own weapons. However, some far wiser have already pointed out that if a cell phone can be blocked, so can a smart gun. Thus negating the ability to use the weapon at all. The blockers are not really all that sophisticated. Any self-respecting jihadist engineer could discover the secret.
The wiser ones also mentioned that once (if) the technology is out there, someone will learn easier methods to defeat it. For instance, knock the victim senseless, grab their wrist, put it next to their head, put the gun next to the hand, and well, the rest is easy to see. Or design a system that turns all electronic guns on - or fries the power circuits in the guns. And God forbid an EMP strike. All electronic guns over thousands of square miles rendered inoperable. What a usefull device.
