Police agencies are allowed to use ANY public service bands in
their city that are not being used by other city departments.
Thus, if a channel is licensed to a city's service department,
but that department doesn't use it, the police may LEGALLY make
use of that channel.
That's the law.
That also means they may use an active channel licensed to another
city department whenever that department isn't using it, such as
using the garbage collection channel at night when the garbage
crews aren't working. In fact, to be technical about it, since
only one person can use a channel at one time, the police can
use any city channel. After all, at the moment the police and
dispatcher are transmitting, the other city department licensed
to that channel isn't using it.
As for legal ID's...someone said stations must identify themselves
every 30 minutes. Not true. Stations must identify themselves
every time they begin transmitting. If a city's dispatch service
is identified as KQA 934 (just an example, don't go looking to see
who KQA 934 is...or if it even exists), as soon as a broadcast
from dispatch begins with, "934 to car 12," it has legally identified
Stations that transmit continuously (no break in the carrier) are
required to identify themselves once an hour as close to the top
of the hour as possible. The automatic morse code broadcasters
that automatically run a coded ID every 10:00 or so cover a
licensee's backside in case the radio operators don't identify
themselves as required.
Someone also wrote asking why the use of Morse code when nobody
uses Morse code these days. Obviously, somebody uses Morse code.
It's just that the person who wrote that isn't one of those people.