In 1929, Cooper declared his candidacy for county judge of Pulaski County. His opponent, the incumbent, was the president of Somerset Bank and the former law partner of Cooper's father. Cooper won the election, however, beginning the first of his eight years as county judge. During his service, he was required by law to enforce eviction notices, but often helped those he evicted find other housing or gave them money himself, earning him the nickname "the poor man's judge". He reportedly became so depressed by the poverty and suffering of his constituents during the Great Depression that he had a nervous breakdown and took a leave of absence to seek psychiatric treatment.