William Henry Harrison Hart (October 30, 1857 – January 6, 1934) was an African American attorney and professor of criminal law at Howard University from 1887 to 1922.

His father was Henry Clay Hart, a white slave trader born in Providence, Rhode Island, in 1829.

He was a descendant of Thomas Hart, an English jurist who embarked at Baddow, Essex county, England, in the Desire, in 1635, landing at Ipswich, Massachusetts, in 1639.

[3][5] The Maryland Legislature enacted a Jim Crow Law in 1904 that required steamship lines and railroads to maintain separate but equal facilities.

[8] A number of people were arrested in the following weeks, but the practical and legal workings of the Jim Crow Law got its first real test in the early autumn of 1904.

William Henry Harrison Hart and his sister, Clementine Bartlett, refused to move to the "colored car."

The lawyer was given the choice of the proper car or jail, and refusing the former was escorted to a cell," the Cecil Whig reported.

Hart was on a through train from New York to Washington so the decision of the lower court was reversed, but the law was sustained in Maryland.

[13] So long as Hart was crossing state lines (rather than engaged in intrastate travel), the racial segregation laws could not apply.