Forcing companies to disclose harmful chemicals in their products sounds like a no-brainer. It did for a majority of voters in California, who in 1986 adopted such a measure, known as Proposition 65. But what if you're certain your product contains too little of a toxic substance to pose any threat, and including it on a label would scare customers away?

Accused of failing to warn consumers about lead in baby food, Beech-Nut Nutrition Corp. and other major food companies turned to Morrison & Foerster, where partner Michèle Corash has been battling Prop 65 since before it became law. Corash's efforts paid off this week, turning a potential nightmare for the companies into a litigation victory that's bound to have ripple effects for other businesses.

Six weeks after Corash argued for all the defendants, California's First District Court of Appeal sided unanimously on Tuesday with Beech-Nut, Dole Foods Inc., Gerber Products Co. and 13 other companies that make baby food, fruit juice and packaged fruit. The Environmental Law Foundation had sued the companies in 2011, alleging that their products contained lead at levels that warranted warnings under Prop 65. But the court rejected ELF's measure of lead exposure, upholding an earlier win for the food companies and tossing the case.