It is unclear whether Congress has the constitutional authority to impose ethics requirements on Supreme Court Justices, a question the Court may have to decide.[20] In 2011, Chief Justice John Roberts made clear in his end-of-year report that he believed Congress does not have the power to impose conduct rules on the Supreme Court, because the Supreme Court was established by the Constitution, according to which the justices serve as long as they exhibit "good behavior", or face possible impeachment and removal for "treason, bribery, or other high crimes and misdemeanors".[21] Lower federal courts, by contrast, were created by Congress and are subject to rules Congress establishes. Because of this, some suggest that the purpose of the proposed ethics rules would not be punishment or even enforcement, but only a promulgation of rules so that Supreme Court justices can be held accountable for their conduct in the court of public opinion. In addition, a documented ethics violation could be relevant to a potential impeachment proceeding.[22] Others argue that Congress has the authority to require the Supreme Court to write its own code of ethics.[23] In 1991 the Supreme Court adopted a resolution[24] that its officers and employees will comply with the substance of the Judicial Conference Regulations,[25] subject to stated clarifications.