Dong Zhongshu
Under the advice of Dong Zhongshu, Emperor Wu ordered each district to recommend one filial and one incorrupt candidate for civil offices. Later the nomination became proportional; Emperor He of Han changed the proportion to one candidate for every 200,000 residents, and one for every 100,000 residents in ethnic minority regions. The nominator was also responsible if the nominee was charged with corruption, and could be punished if he refused to nominate qualified individuals.