June 13 (Reuters) - The ex-chief judge of the top U.S. patent court will retire at the end of June, after acknowledging that an email he sent raised questions about his judicial ethics because it praised an attorney who appears before the court.
Judge Randall Rader of the U.S. Court of Appeals for the Federal Circuit previously stepped down from his leadership position on May 23. His retirement is effective June 30, the court said on its website on Friday.
Rader did not respond to an email seeking comment.
The Federal Circuit, which has exclusive jurisdiction over patent appeals, has become increasingly important in recent years due to high-stakes litigation over technology patents. It has been frequently divided over issues like software patents.
In an open letter posted in May when he stepped down as chief, Rader said he had "engaged in conduct that crossed lines established for the purposes of maintaining a judicial process whose integrity must remain beyond question."
His decision at the time followed a report by the Wall Street Journal on an email Rader sent to Edward Reines, a lawyer at law firm Weil Gotshal & Manges, praising his work.
Reines represents software company Microsoft Corp and medical technology group Medtronic Inc in two separate cases before the court, according to the docket. He did not reply to an email seeking comment about the judge.
Rader later recused himself from the two cases as a result of his email, a move made public via court orders. His stint as chief judge, mainly an administrative role, was due to end in 2017.
While Rader did not mention Reines by name in his May letter, he said the email "constituted a breach of the ethical obligations not to lend the prestige of the judicial office to advance the private interests of others."
Rader was appointed to the court by President George H.W. Bush in 1990 and became chief judge in 2010. (Reporting by Nate Raymond in New York; Editing by David Gregorio)