It's kind of the swiss cheese model. People will slip up--it's very hard to conduct business in entirely off-the-record chats. I like the recent example of a j

It's kind of the swiss cheese model. People will slip up--it's very hard to conduct business in entirely off-the-record chats. I like the recent example of a junior BP trader. He had an opportunity to meet a vice president of the company, and was trying to impress the VP with what the trader's team was doing. The VP responded along the lines of "Gosh, it's funny, what you're describing almost sounds like market manipulation, but it can't be, because I'm sure we wouldn't be doing that." The junior BP trader then immediately called the senior trader on their office phone. All calls to the office phone are recorded. Throughout the call, the junior trader is persistently trying to ask if what they're doing is market manipulation, and the senior trader keeps cutting him off before he can complete a sentence. Then the penny drops, the junior trader says, "Hey, I just remembered, I need to run," hangs up, and immediately calls the senior trader on his (unrecorded) cell phone. _That_ call wasn't recorded, and when asked in court, neither the junior trader nor the senior trader could recall what they discussed. The judge didn't seem to believe them. BP had to pay a bunch of $, and the junior trader now works somewhere else. :)