Chief Justice John G. Roberts Jr. has turned down an invitation to testify before the Senate Judiciary Committee to discuss Supreme Court ethics rules. In a letter, Roberts stated that appearance before the committee was “exceedingly rare” and could be considered a risk to judicial independence. This letter came after Senator Richard J. Durbin invited the chief justice to testify in light of revelations of unreported gifts, travel, and real estate deals between Justice Clarence Thomas and Republican donor Harlan Crow.

Roberts included an appendix of the relevant laws that apply to judicial disclosures and a “statement of ethics principles and practices” signed by all nine Justices. The signed statement insists that existing rules around gifts, travel, and other financial interests are sufficient. The Justices also wrote that they would look to “judicial opinions, treatises, scholarly articles, disciplinary decisions, and the historical practice of the court and the federal judiciary” to help resolve ethical questions.

This decision to decline the invitation points to an ongoing debate over Supreme Court ethics and transparency. The statement from Chief Justice Roberts and the other eight justices comes amid increased scrutiny over unreported real estate deals and private travel arrangements made by Justice Thomas. The Senator Durbin controversy highlights the difficulties faced by Congress in bringing about bipartisan agreement for reform that the Justices themselves do not want.