As a law enforcement professional, it is tactically wise to have options, and to recognize what they are. Most officers will tell you that edged weapons are dangerous and abide by the standard 21’ rule. And most defensive tactics / arrest control programs offer a cursory segment in “defensive” techniques. However, that is only half of knife tactics training. What about the offensive portion?
The majority of LE professionals carry some type of knife on them, typically as a “utility tool.” However, many of those officers may fail to recognize the significant capability of the tactical knife as a second deadly force option.
When would an officer utilize a knife as a second deadly force option? What if your firearm is not accessible? Say it was lost in a struggle or foot chase (it happens). You may also resort to a knife in a weapon retention scenario, following a fatal malfunction with your sidearm, or if surroundings make it unsafe to discharge a firearm.
As you can see, edged weapon/knife tactics covers more than just counter-measures against spontaneous attacks on the officer, and most “defensive” training is just that, defensive/re-active.
Bottom line is this: It is always wise to be intimately familiar with your auxiliary weapons and the tactics involved in using them. A knife is a deadly weapon, whether you are using it offensively or countering against it. If you are going to carry a knife, you should make sure you are trained appropriately with it. This can/will help cover you during the inevitable second guessing and court battles.