I'm not a cop and I don't know any but I can't think of a time or reason when a cop would need a knife with a strong lock. IMO, as others have stated, if you're using a knife correctly as well as using the right knife for the right job, you shouldn't ever need a strong lock. This occurred to me when I got a UKPK. I realized that 99% of normal knife use requires no lock at all. The only time I can think of a lock needing to be "strong" or "heavy use" is when pressure is being put towards closing the blade, which only happens when stabbing/ piercing pressure is applied in a real world sense.
Edit: I suppose sawing would create some pressure on the lock but again, I think this boils down to using the right tool for the right job. If you need to saw something with a good amount of force, you shouldn't be using a folder anyway.
When do cops ever need to get in a knife fight? NEVER!
Cops probably never use their knives for anything besides cutting people out of cars and opening bags of chips/candy while on the road. Has anyone ever heard of a cop using a knife as a weapon or even being in a situation when a strong "heavy use" knife was needed? ...I doubt it.
The Spyderco Military is an awesome knife and one of the best examples of a MW liner-lock there is on the market, IMO. Needless to say, Sal knows what he's doing.