It's rather rare these days to see collusion lawsuits where there's overt evidence of collusion. Instead, it's usually implicit collusion where a case needs to be made that this is a problem. However, every once in a while you still get those good old fashioned situations where there's evidence of direct price fixing. For example, the Inquirer points us
to a case involving questions of collusion in the graphics card market between ATI and NVIDIA, where it appears NVIDIA's VP of marketing sent an email to ATI's president and chief operating officer
suggesting that, while the two companies were competitors, they should work more closely to make sure their stock prices each remained high. Apparently, the lawyers in the case tried to hide that document as a "trade secret." If you consider it to be a "trade secret" that the two companies may have been collaborating, then perhaps they have a point. But the judge didn't buy it: "This court is not a wholly-owned subsidiary of your companies. I am against you hiding information from the public."