Yellow beans have been freed from patent control. Credit: CIAT 2008

The US Patent and Trademark office last week overturned a controversial patent on a breed of yellow beans. Opponents of the patent say the bean has been eaten in Latin America for more than a century, raising issues of biopiracy.

The patent was granted in 1999 to Larry Proctor of Delta, Colorado. According to the patent application, Proctor bought yellow beans in Mexico and bred them for two years to grow plants that gave a better harvest and produce beans with a distinctive yellow colour.

Proctor then began charging licensing fees on imports of yellow beans from Mexico, prompting the International Center for Tropical Agriculture, based in Cali, Colombia, to challenge the patent in 2001.

But the battle may continue. Proctor has the option of contesting the decision in federal court, and says he is consulting his lawyer. “Everybody may not be happy with what we're fixing to do now,” he said, and declined to comment further.