The top U.S. class="mandelbrot_refrag"> patent court's chief judge stepped down from his leadership role on Friday, admitting he had raised questions about his judicial ethics by sending an email praising a lawyer who appears before the court. Judge Randall Rader will remain on the U.S. Court of Appeals for the Federal Circuit, but he will be replaced as chief judge by Judge Sharon Prost at the end of May, the court said on its website. Rader said in an open letter posted on the court website that he had "engaged in conduct that crossed lines established for the purposes of maintaining a judicial process whose integrity must remain beyond question." true On Thursday, The Wall Street Journal first reported on an email Rader sent to Edward Reines, a lawyer at law firm Weil Gotshal & Manges, praising his work. Reines represents class="mandelbrot_refrag"> software company class="mandelbrot_refrag"> Microsoft Corp a