Ebenezer Rockwood Hoar, an American jurist, born at Concord, Mass., Feb. 21, 1816. His father, Samuel Hoar, was sent in 1844 by Massachusetts to South Carolina as a commissioner to test the constitutionality of the act of that state under which free colored citizens of northern states were imprisoned and sometimes sold. The son graduated at Harvard college in 1835, studied law in Cambridge, and was admitted to the bar in 1840. He was appointed judge of the court of common pleas in 1849, but resigned in 1855 and resumed practice in Boston. In 1859 he was appointed a judge of the supreme court of Massachusetts, and retained this office till 1869, when he was appointed by President Grant attorney general of the United States. He held this office only one year, but during that time reorganized it, by authority of congress, as a distinct department of the government, under the title of the department of justice. In 1870 he was nominated a justice of the supreme court of the United States, but was not confirmed by the senate.

He was a member of the joint high commission which negotiated the treaty of Washington in 1871. In 1872 he was elected representative in congress from the seventh district of Massachusetts. In the spring of 1874 he was an unsuccessful candidate before the legislature of Massachusetts for the seat in the United States senate vacated by the death of Charles Sumner.