David Kappos has overseen a sea change for the patent system, but now he is leaving his post as office director of the U.S. Patent and Trademark Office (PTO), effective January 2013.

Kappos has been with the PTO for three and a half years, during which time Congress passed the America Invents Act, an extensive overhaul of the patent system which, notably, moved the U.S. from a “first to invent” to a “first to file” system.

With Kappos at the head, the PTO also cut significantly into its heavy backlog of patent applications—from 750,000 in 2008 to 605,000 today—and set up satellite offices in Dallas, Denver, Detroit and San Jose.