Nikolai, side thought re:Lying in fiction is "fiction", and therefore not on the same level:
I believe that this is true on one level but not on another. It is certainly true that if you write a story in which you have JFK as being abducted by aliens and replaced with a synthdroid and "assassinated" in order to provide a feasible way to get the synthdroid (which isn't that intelligent and has a short battery life) out of the picture, and then it turns out that the aliens took JFK in order to have him lead an intergalactic armada against an evil empire that wants to enslave the universe... well, that'd probably be fine. People would say, "Okay, yeah, that's fiction."
In fact, if you wrote a thriller involving JFK that focused on his assassination being a mob hit because he'd gotten a mafia daughter pregnant (and you made up the name of the mafia daughter), you'd also be fine.
If you used a real person for the mafia daughter, you'd be treading close to the line, though, in terms of being legally accountable in some coutries.
This is all just what I remember, though. It was something mentioned in a writing class. Having a character say, "I don't like Pepsi" or "What's wrong with this Pepsi? It tastes like it's been mixed with battery acid," is fine, because it only promotes a personal character viewpoint or an indication that one particular can of Pepsi has something wrong with it.
Having a character say, "I don't drink Pepsi, and you shouldn't either, because it's made from the ground-up bodies of twenty-third century freedom fighters whose remains are sent back in time to hurt morale in the resistance," is also probably fine, because, while gruesome, your statement is silly enough to be taken as fiction.
However, what if, in a work of fiction, you have a character say, "Oh, the cause of death was Pepsi. The man had an increasingly common type of stomach condition caused by too much protein and fat hitting the system -- the whole Atkins, South Beach thing. It's not much of a problem, except that 1 case of Pepsi out of every 6 that's purchased in the U.S. is actually made in Mexico, and Mexican water systems are years behind U.S. in terms of chemical safety. One out of every hundred cases of Mexican Pepsi have a broken-down agricultural pesticide in their water at a small level. For an ordinary person, this just makes the Pepsi taste a bit funny, maybe a bit more bitter than usual. But for someone with the Atkins-diet stomach condition, that chemical leads to an almost-immediate bleeding ulcer and serious long-term health problems. So basically, for someone on the Atkins diet, one can of Pepsi out of every 600 is poisonous."
Well, you'd have Pepsi, Atkins, and Mexican labor sources all up in your face in a heartbeat. They'd go after you for slander, arguing that what you wrote wasn't intended as fiction. It was intended as fact presented as background for a fictional story -- and it was, in that context, not a piece of fiction, but a lie.