Gertrude Rothschild. Credit: K. TANNENBAUM

An octogenarian physicist is taking on the world's largest electronics companies, which, she claims, have infringed her patent for making blue and ultraviolet light-emitting diodes (LEDs) and short-wavelength laser diodes.

On 20 March, the International Trade Commission, which oversees imports to the United States, announced it would investigate a complaint filed by Gertrude Neumark Rothschild, a professor emeritus at Columbia University in New York City. The complaint names some 30 companies, including Sony, Toshiba and Motorola.

Rothschild was awarded a patent for a process used to make wide-band-gap semiconductors in 1993. She had found an affordable way of making the semiconductors' resistivity low enough to make them commercially useful. It eventually allowed green, blue and ultraviolet LEDs and solid-state lasers to become common components in everything from mobile phones to the latest generation of DVD players.

Exactly how companies are producing the diodes is unknown because of trade secrets protection, but there is good reason to believe that Rothschild's process is being used, according to Albert Jacobs, the physicist's lawyer at Dreier, a New York firm. “We believe that her patent covers the only viable commercial process,” he says. The companies contacted by Nature declined to comment on the case.

Rothschild has taken on the electronics industry before. In 2005, she filed suit in federal court against two other companies: Toyoda Gosei of Japan and and Philips Lumiled. Both were settled out of court. But the trade commission complaint is further-reaching than the previous suits. If the commission finds in her favour then it may order the companies to cease and desist production, or ban the import, of equipment that contains the relevant technologies.

Rothschild says that she filed the complaint in part to raise awareness of women's role in science. “People don't pay too much attention unless there's a financial impact,” she says.

This is not the first time that blue LEDs have been the subject of an intellectual-property dispute. In 2004, a Tokyo court awarded Nichia Corporation researcher Shuji Nakamura ¥20 billion (US$180 million) for his role in their development. This was later reduced to ¥840 million after appeal.