US Circuit Judge Randall Rader, who was just weeks ago the top patent judge in the nation, has announced he will step down, following an admission that he made an ethical "lapse" when he sent an e-mail praising an attorney who appears frequently before his court.

From 2010 until two weeks ago, Rader served as Chief Judge on the US Court of Appeals for the Federal Circuit, which hears all patent appeals and interprets most of the nation's patent laws. The Washington, DC-based court is frequently the final arbiter in some of the highest-stakes technology battles in the world.

Rader stepped down following the release of an e-mail to attorney Ed Reines, a patent lawyer at Weil, Gotshal, and Manges, who frequently practices before the Federal Circuit. In the e-mail, Rader praised Reines' performance at a recent argument and encouraged him to share the e-mail with others.

"I have come to realize that I engaged in conduct that crossed lines," Rader explained in an open letter published on May 23. While he said he "would never compromise my impartiality in judging any case," he said that by encouraging Reines to share the e-mail, he "realize[d] in retrospect that the e-mail constituted a breach of the ethical obligation not to lend the prestige of the judicial office to advance the private interests of others."

In that letter, Rader said he would step down as Chief Judge but remain on the court. On Friday, however, Rader announced he will retire altogether.

Parts of Rader's e-mail to Reines were obtained and published by Scott Graham of The Recorder, a San Francisco legal newspaper. The e-mail describes a female judge—presumably Circuit Judge Sharon Prost, the only woman on the panel in question—being impressed by Reines' arguments, comparing him favorably to opposing attorney Seth Waxman. Rader wrote:

She said Seth had a whole battery of assistants passing him notes and keeping him on track. You were alone and IMPRESSIVE in every way... in sum, I was really proud to be your friend today! Actually, I not only do not mind, but encourage you to let others see this message.

"Not happy" after leaving top spot

On the thorniest issues of patent law, Rader often came down on the side of having an expansive view of the power of patents. In the fractured Alice Corp. v. CLS Bank case now being reconsidered by the Supreme Court, Rader wrote a full-throated defense of software patents.

Reuters published a profile of Rader last year, explaining how the judge gave up to 100 speeches a year, many of them abroad, "extolling the American patent system that his court oversees."

Rader had a colorful personality for an appeals judge: he sang vocals in a rock band, often playing Van Morrison and the Rolling Stones at legal conferences. At the same time, he's a practicing Mormon who said he "never intentionally consumed alcohol," but once accidentally drank from a spiked punch bowl.

A lifetime government employee, Rader worked as a lawyer in both houses of Congress. He was appointed to the US Court of Federal Claims in 1988 and to the Federal Circuit in 1990.

Rader wrote a note about his resignation to the IAM Blog, part of Intellectual Asset Management magazine. "The bottom line is that I was not happy after leaving the Chief position and it hit me that I need to leave while I am young and full of energy to change the world," he wrote. He explained that he plans to teach IP law at universities in China, Japan, Korea, and Germany. "My Dream Job: travel, friends, and teaching—what I love!" wrote Rader.

Reines, the attorney to whom Rader sent the e-mail, often works on big tech cases. He's represented Yahoo in its fight against the much-maligned Eolas patent and Newegg in its battles against Alcatel and Soverain Software's "online shopping cart" patent.

Contacted by Ars, Reines declined to comment on Rader's resignation.