can police scanners pick up cell phones?

Older scanners, made and sold before cellular phones went digital and into the newer frequency bands could indeed monitor analog and unencrypted cell phone transmissions.

In 1994, the FCC and congress passed an act that made it illegal to monitor cellular phone transmissions and also made it illegal to modify a scanner to monitor cell phones. Also at this time, scanner makers started making scanners that blocked certain 800MHz and 900MHz frequency ranges.

In today's world, cellular phones are no longer analog, they are digital. They also use encryption methods to make them more secure and better signal. Scanners made or sold today anywhere in the world can not monitor cellular phones.

Some old scanners (made before blocking was required) can pick up some (older technology) cell phones. But for the most part, no.

Technically yes they can. However, the FCC mandated that cellular frequencies be blocked to comply with privacy laws.

The penalties for getting caught illegally listining to a phone conversation are steep.

If you want to get real technical though, a cell phone is actually a two way radio and not a phone.

YES.... If purchased in the U.S. the cell frequencies are blocked, but not in Canada. You can buy a scanner in Canada, bring it here, and listen to your neighbors phone sex.

No. But, if they have sufficient reason to, they can get a subpoena, and get the feds to do it. I'm sure all the NSA needs to do is plug in your phone number to listen in ;)

No, it is illegal for them to receive in those bands.

No