Representative Denis O’Leary

Denis O’Leary (January 22, 1863 – September 27, 1943) was an American educator, lawyer, and Democratic politician who served as Queens County district attorney and for one year as a member of the United States House of Representatives from New York, from 1913 to 1914. His public career spanned the late nineteenth and early twentieth centuries, during which he participated in the democratic process at both local and national levels and represented the interests of his constituents during a significant period in American history.

O’Leary was born on January 22, 1863, in Manhasset, Long Island, New York. He was educated in the public schools, and after completing his own studies he remained in the system as a teacher, beginning his professional life as an educator. This early experience in public education helped establish his connection to local communities and public service in the growing metropolitan region surrounding New York City.

Pursuing a legal career, O’Leary enrolled in the law school of New York University, from which he was graduated in 1890. He was admitted to the bar the same year and commenced the practice of law in New York City. His legal work in the city placed him within the expanding legal and political networks of New York at the turn of the century, providing a foundation for his later roles in municipal and county government.

O’Leary entered public legal service as assistant corporation counsel of New York City in 1905 and 1906, a position in which he assisted in representing the city’s legal interests. He subsequently served as commissioner of public works of Queens Borough in 1911 and 1912, overseeing aspects of municipal infrastructure and public improvements during a period of rapid urban development in the borough. These appointments enhanced his visibility in Queens and prepared him for elective office.

Elected as a Democrat to the Sixty-third Congress, O’Leary represented New York in the United States House of Representatives and served from March 4, 1913, until December 31, 1914. His single term in Congress coincided with the administration of President Woodrow Wilson and a period of major legislative activity at the federal level. O’Leary resigned his seat on December 31, 1914, after deciding to leave national office in order to pursue a key local post in law enforcement in his home county.

Following his resignation from Congress, O’Leary was elected district attorney of Queens County, serving from 1915 to 1921. In that capacity he was responsible for prosecuting criminal cases and directing the work of the county’s prosecutorial office during years of significant growth and change in Queens. His tenure as district attorney further solidified his reputation as a prominent legal and political figure in the borough.

After completing his service as district attorney, O’Leary resumed the private practice of law. He continued in legal practice until 1929, when he retired from active professional life. In retirement he remained a respected elder statesman in Queens, associated with decades of public and legal service that had encompassed education, municipal administration, county prosecution, and national legislative work.

Denis O’Leary died in Douglaston, Queens County, New York, on September 27, 1943, at the age of 80. His career reflected the trajectory of a locally rooted New York lawyer who rose to national office and then returned to concentrate on the legal and civic affairs of his home county.