The Auditing Yuan (審計院) was established in February 1928, but in February 1931, the Control Yuan, exercising the powers of auditing and impeachment, was formed to serve as the highest supervisory organ of the Nationalist Government. At the same time, the Auditing Yuan was downgraded to a ministry and incorporated into the Control Yuan. In 1937, following the outbreak of the Sino-Japanese War, the powers of censure and audit were added to the Control Yuan.