PIAC- That used to be a law, I believe, but they eventually repealed it. All that's required now is a disclaimer saying you're not in any way associated with the product you're bashing.
"I recall, back in the days of the N64, either Sega or Sony liked to show a commercial in which people shot N64 consoles into the air and shot them as clay pigeons, which appeared very childish in contrast to Nintendo's advertisements that refrained from such immature nonsense."
I haven't actually seen the commercial, but I think it was Sega- Sega was very famous for slandering Nintendo (does what NintenDON'T). I also remember Sega releasing an odd expressing their "condolences" over Sony's PS2 shipping problem, to which Sony replied appropriatley. Odd how everyone says Nintendo's the kiddy one.