People record all kinds of things. The issue is the context in which they are communicated. For years the cassette recorders used in interview rooms were the evidence - but for that evidence to be accepted in court, the recording needs to be able to be validated by forensic specialists = to stop people editing them to make it appear the conversation was different. The edit is quite simple to do, but the tapes have the conversation on one track and a time reference on the other, so with two copies, you can prove they have been Tampered with. Recording somebody covertly and making them say things they did not would be simple to do - but the judge would have to rule on it's acceptance. I assume the usual libel and slander rules would be the key feature. Private detectives do it, the security services do it, and youtube is full of Rec wordings of people kicking off. Nothing ever happens?