Before I subject myself to the inevitable barrage of negative responses, let me qualify my statements. I am a firearms instructor, and I am trained in SWAT tactics, hostage rescue, etc. By no means am I anti-gun, quite the contrary, I enjoy shooting and am very officer safety oriented.
I have two problems with back-up weapons, one from an instructor standpoint, the other from a chief's view. First, I would ask all of you to take a look at your individual departments. How many of your co-workers actually "train" as opposed to just doing mandatory qualification? Qualification isn't enough to make you proficient in the use of one weapon, let alone two. For those of you that do carry a BUG, do you practice retrieving that weapon and firing it in any sort of tactical simulation? If you don't, the chances of you retrieving that weapon and deploying it effectively under stress is very thin. You are talking about employing fine motor skills for which you have not acquired any muscle memory. Under stress, fine motor skills go out the window unless they have been practiced. There is also a concern with handgun retention. Can you effectively retain two weapons?
From the Chief's perspective...you have to remember, policies and training have to be to be written to cover the "worst officer" scenario. We all know the guy who hasn't broken leather or even cleaned his weapon since the last qualification! This is the guy keeping you from carrying a BUG, not the Chief. Many of you will say, "Well punish him, not me". You all know that this type of selective policy enforcement would bring hell-fire from your unions.
I would venture to guess (I have no statistics) that the number of times an officer has saved his bacon with a BUG pales in comparison to the number of officers shot with their own weapon. If someone were to attempt to disarm you of your primary, you may pull out your BUG and avoid being shot, but as I stated earlier, without "real" training, it probably ain't gonna happen. What you have done by bringing another weapon into the mix is actually increase your chances of being shot by one of your own guns.
Be honest with yourselves. How many of you actually train aside from qualifications? For those that do, and are willing to notch up the amount of time you spend training to include a BUG, I commend your commitment, and you should be allowed a BUG. For those that don't, BUGs are a bad idea.
But then again...what do I know? 8)