Director of the US Patent and Trademark Office Michelle Lee resigned today, without explanation.

Lee, who has been director of the office since 2014, was a favored candidate by the tech sector, who thought she brought a balanced approach to patents. She is a former Google lawyer and was one of the first corporate lawyers to speak out about the problem of so-called “patent trolls.” Lee took office at a time when the tech sector was at odds with the pharmaceutical lobby and trial lawyers over a proposed patent-reform law, which did not end up passing.