The S.C. Supreme Court asked attorneys for Gov. Mark Sanford Wednesday to explain why a letter Sanford signed opening to the public an Ethics Commission probe into his travel should no longer apply. Sanford has asked the state’s highest court to prevent lawmakers, who are expected to file impeachment charges against Sanford, from getting an initial investigative report from the S.C. Ethics Commission. The report, expected to be wrapped up next month, will outline the case against Sanford and the evidence supporting it. Sanford argues releasing the report would unfairly undermine his defense. But Sanford agreed to waive his right to confidentially in the probe in a letter he wrote to the commission. The court wants Sanford to explain why the letter should not apply to this report. The S.C. Ethics Commission is investigating Sanford’s use of the state plane, his reporting of private airplane rides and his use of campaign funds.