(FORTUNE Small Business Magazine) - Who knew that a pinhole could be worth billions? In October 2003 we wrote about inventor Jack Evans, who was in a court battle with General Motors ("Fast and Furious"). Evans claimed that GM stole his design for an engine cooling system when he worked as a consultant for the company in the 1980s.

He filed a $600 million lawsuit in 1994, accusing GM (Research) of using his design - built around a vent no larger than a pinhole - in millions of cars and trucks. Although GM admitted that an employee had forged evidence to support its claim that it had developed the cooling system independently, a Connecticut judge found in favor of the automaker.

But in late March the Connecticut Supreme Court overturned that decision, ruling that the judge should have allowed the inventor to plead his case to a jury. The second trial should begin by the end of the year, and the stakes are high: GM's law firm says the automaker's potential liability could be as high as $12 billion.