The FBI's apparent courthouse or near-courthouse tapping took place in California. If you placed microphones in random public places in CA, the question would b

The FBI's apparent courthouse or near-courthouse tapping took place in California. If you placed microphones in random public places in CA, the question would be whether there's an expectation of privacy in a conversation that took place in or near those places. If someone does have an expectation of privacy in public (which does not necessarily seem clear to me), you would be engaging in unlawful surveillance. Whispered conversations in public may be protected. The language used by CA law is: "circumstance in which the parties to the communication may reasonably expect that the communication may be overheard or recorded." See: http://www.leginfo.ca.gov/cgi-bin/displaycode?section=pen&group=00001-01000&file=630-638 http://www.leginfo.ca.gov/cgi-bin/displaycode?section=pen&gr... In CA, video recording laws are more liberal. That's why you see surveillance cameras all over the place in cities (and increasingly in residential suburban or rural neighborhoods as well).