Though TB is a pretty good powder with a wide range of uses in various calibers, I have not heard of "Law Enforcement Loads" referred to when using it. Now, Silhouette... that's a different matter as it is the clone of the original powder (WAP) used when the .40 S&W was invented, and is still my "go to" powder in that caliber as well as for upper mid-range to max loads in several other calibers of the "defense" variety.
57K certainly likes TB, but he likes Silhouette too, and for zippier loads Silhouette is generally preferred with a few exceptions like 357 Magnum perhaps. Still... if you are only buying one powder, True Blue would not be a bad one to have and is pretty much the "ball powder" Unique in that it has a very wide range of uses, though personally I still like Silhouette.
I, Procrastitron will destroy evil.... eventually.