A Los Angeles judge ruled [text, PDF] Wednesday that coffee companies are required to display cancer warning labels on coffee because of the chemical produced in the roasting process.

The Council for Education and Research on Toxics, a non-profit group, sued several coffee roasters, distributors and retailers under Proposition 65, a California law that requires [WP report] products that contain carcinogens to have warning labels. The long-running lawsuit, which was first filed in 2010, raised the issue [LAT report] of whether coffee drinkers should be warned about acrylamide, the chemical in question.

In a tentative decision, Superior Court Judge Elihu Berle wrote [proposed ruling, PDF]:

While plaintiff offered evidence that consumption of coffee increases the risk of harm to the fetus, to infants, to children and to adults, defendants’ medical and epidemiology experts testified that they had no opinion on causation. … Defendants failed to satisfy their burden of proving by a preponderance of evidence that consumption of coffee confers a benefit to human health.

The judge has given the defense several weeks to object to his proposed ruling before it is finalized. A third phase of trial will determine the penalties that Starbucks and other coffee companies will have to pay.