SAN FRANCISCO — Randall Rader resigned as chief judge of the U.S. Court of Appeals for the Federal Circuit on Friday, admitting in an open letter he’d made ethical missteps.

Rader apologized for “conduct that crossed the lines” when he sent an email to Weil, Gotshal & Manges partner Edward Reines praising Reines’ skills and encouraging him to share the email with others. In perhaps a more serious transgression, Rader also conveyed a Federal Circuit colleague’s enthusiasm for Reines’ performance in two cases he’d just argued to the court.