Not at all. The 24 channel is the same band as the 40 channel, just with 16 fewer channels. CB stands for citizens band which is an AM range of radio. Police operate on a completely different FM band which can't be heard on CBs any more than AM radio stations can be heard on an FM radio.
The FCC regulates what frequencies you're allowed to transmit. CB under 4w TX is open territory, and the new Family band (like the little talkabouts) under 1w are open territory. Anything that falls outside these ranges needs an FCC license to transmit. There are still some short wave transmissions that don't require a license I think, but they're not anything that someone would really use these days.
Once its transmitted, though, its free range. You can legally use a police band scanner to listen in on what they're saying. That's one of the reasons for the "10" codes and crime codes. If they broadcast that there is a fire at the grocery store on main and Officer Smith is on the way, everyone with a scanner would show up to watch Officer Smith and a fire. Instead they say something like there's a 4412 in progress at 212 main, 141, 10-12.
Whenever you hear about some egghead listening in to NASA transmissions and breaking the code, they can't legally be arrested for listening and understanding. They can be taken out with a sniper because now they know too much
