Some of his colleagues said Lessig's departure is a great loss to the school.

"We are sorry to see Lessig leave HLS," said Assistant Dean of Academic Affairs Stephen A. Ray. "He has been a strong contributor to our curriculum."

In previous semesters, Lessig has taught a range of courses, some of which--like "The High-Tech Entrepreneur"--have focused primarily on Internet and software law.

He has also served as a fellow of the Berkman Center for Internet and Society --a research institute on cyberspace and its development.

According to Ogletree, Lessig has played an "integral" role in the program.

Lessig's announcement comes less than a month after a ruling in the Microsoft antitrust lawsuit that found the software company guilty of anti-competitive behavior. In that case, Lessig had advised Judge Thomas Penfield Jackson that Microsoft's policy of "tying" its web browser with its Windows operating system may have given the company an unfair advantage over its competitors.

His role as a friend of the court in the Microsoft case brought publicity to the center and to HLS.