The defendants claimed that Chinese law compelled them to form a cartel to sell vitamin C, and the Chinese government even hired Sidley Austin to support that argument. But the companies still can't escape class action litigation over the alleged price-fixing, a Brooklyn federal judge ruled Tuesday.

A federal judge in Brooklyn agreed Thursday to certify classes of direct and indirect purchasers in a set of suits accusing four Chinese manufacturers of joining a cartel to fix prices for vitamin C. The litigation has drawn a rare U.S. court appearance by the Chinese government, which hired Sidley Austin to back the companies' defense.

It was inevitable that the collapse of the $300 billion auction-rate securities market in 2008 would trigger securities litigation. But the ARS freeze also spawned a massive antitrust case, after a trio of plaintiffs firms cooked up a theory that the market's demise was triggered by an illegal boycott on the part of major banks.

A consolidated antitrust class action against four Chinese vitamin C makers case got smaller--but no less interesting--when one of the defendants agreed to a $10.5 million settlement. "This is the first shoe to drop in a Chinese cartel case, and it's a $10 million shoe," said William Isaacson of Boies Schiller, co-lead counsel for the direct purchaser class.

For litigators, it pays to be both tenacious and creative. For evidence, look no further than William Isaacson's long antitrust crusade against Chinese vitamin C manufacturers, which culminated this month in an historic $162 million jury verdict.