Like some other early mayors of the City of Washington, such Robert Brent and Benjamin G. Orr, Maury was involved in slavery. In the United States Census of 1840, Maury's household included five enslaved people including a boy and a girl under 10 years old. In 1850, Maury reported an enslaved 23 year old female. In 1862, Maury's widow Isabel filed a petition under the District of Columbia Compensated Emancipation Act seeking compensation for a family of six enslaved people who were emancipated under the Act. According to her petition, the family had been willed to her by her late husband. The enslaved were Eliza Dyson and her five children, ages 4 to 15.