I agree with Narcotics, Detectives (especially IA), and some tac channels (Depending on circumstances) being encrypted. There are a few channels on the Michigan State system that I think should be encrypted, but currently are not.
In general, regular dispatch channels should not be encrypted (there are always exceptions, but full time encryption should be avoided).
Here's why I believe this:
1. With open communications, the community becomes an extension of the law enforcement department. Whenever a BOL is issued for a suspect, in many cases it's a citizen, listening to their scanner, that calls in the tip that leads to the apprehension of the suspect. With full time encryption, you lose those extra sets of eyes that can help get people like that off the streets.
2. When I see a department that runs full time encryption, I wonder what it is that they need to hide. These departments eventually get branded as "secret police" agencies, and without the community able to know what the department is up to, eventually the department will have some corruption, it's just human nature.
I think if you really sit down and think about it, you would find that the majority of scanner listeners have no interest in committing crimes, or interferring with the police. They just want to know what's going on around them.
Yes there are criminals that use scanners during the commission of a crime. It's unfortunate that those few criminals add fuel to the fire of these law enforcement agencies that want to stop everyone from listening, just because of that small percentage of people that use scanners for illegal purposes.
Mike