Yancey Lewis (1861-1915) was born in Gonzales County, Texas on August 24, 1861. Lewis received an appointment to West Point, but failed a required mathematics exam. It was rumored that he did this intentionally to avoid military life without rejecting those who gave him the appointment. Instead, Lewis attended Emory and Henry College in Virginia and obtained a B.A. in 1881.
Lewis returned to his hometown and taught school for two years while studying law. He enrolled at the University of Texas in 1883. As a student, Lewis began the Athenaeum Society in 1883 to debate philosophy, current events, art, and literature. On commencement day in 1885, Lewis, along with R. C. Walker and J. H. Cobb, drew up the constitution for the Ex-Students' Association. Lewis received degrees in both law and philosophy in 1885 as a member of the first graduating class of the Law Department. After graduation, Lewis practiced with his father, Everett Lewis, in Gonzales before opening the firm of Lewis and Mathis with L. H. Mathis in Gainesville, Texas in 1887. When that firm dissolved, Lewis practiced with Charles B. Stuart until Stuart was appointed judge of the United States Court for the Indian Territory in 1893. In September 1895, Lewis moved to the Indian Territory to practice with C. L. Herbert and J. H. Hill.
President Cleveland appointed Lewis District Judge of the Central District of the Indian Territory upon Stuart's resignation in December 1895. By virtue of this position, Lewis became an ex-officio Justice of the United States Court of Appeals of the Indian Territory. In 1898, Lewis became a partner in the law firm of Stuart, Lewis, and Gordon and served as counsel for the Creek Indian Nation and the Cherokee Nation. In 1901, Lewis left the Indian Territory to accept a position with the Law Department at the University of Texas. He was appointed Dean in 1902. Lewis resigned the deanship in 1904 to return to private practice, moving to Dallas to practice with Nelson Phillips.
Lewis served as president of the Texas Bar Association in 1908 and was a member of the Town and Gown Club in Austin and Critics' Club in Dallas. He twice attended the Democratic National Convention, in 1892 as a Texas delegate and again in 1900 as a delegate from the Indian Territory.