The court systems of local, state, and federal governments, responsible for interpreting the laws passed by the legislative branch and enforced by the executive branch. These courts try criminal cases (in which a law may have been violated) or civil cases (disputes between parties over rights or responsibilities). The courts attempt to resolve conflicts impartially in order to protect the individual rights guaranteed by the Constitution, within the bounds of justice, as defined by the entire body of U.S. law. Some courts try only original cases, whereas others act as courts of appeals. The ultimate court of appeals is the Supreme Court. On the federal level, the system of checks and balances empowers Congress to create federal courts, and all federal judges must be appointed by the president and confirmed by the Senate. The courts may exercise the powers of judicial review and injunction.