William Peter Van Ness (February 13, 1778 – September 6, 1826) was a United States district judge of the United States District Court for the District of New York and the United States District Court for the Southern District of New York, also notable for serving as Aaron Burr's second in Burr's duel with Alexander Hamilton.

Van Ness was born on February 13, 1778, in a portion of Claverack, New York that later became part of the town of Ghent^[1][2][3] Van Ness attended Washington Seminary^[4] graduated from Columbia College (now part of Columbia University) in 1797^[5] and read law with Edward Livingston in 1800.^[1][6][7] He practiced in New York City from 1800 to 1801.^[1][8] In 1801, Van Ness served as a delegate to the New York Constitutional Convention, which was called to amend the state constitution of 1777.^[9] He continued private practice in Albany, New York starting in 1801 and in Hudson, New York, before resuming private practice in New York City until 1812.^[1][8]

Van Ness, a close friend of Aaron Burr, was an active participant in the 1800 presidential campaign as a vocal supporter of the Democratic-Republican Party candidates Burr for Vice President and Thomas Jefferson for President.^[11] Burr and Jefferson tied in the electoral college, and the election moved to the United States House of Representatives, where Federalists wanted to defeat their great enemy, Jefferson, by electing Burr as President. Van Ness secretly supported the Federalist plan, but it failed, and Jefferson won the presidency, with Burr chosen for the vice presidency.^[12]

In July 1804, Van Ness served as Aaron Burr's second in Burr's duel with Alexander Hamilton.^[13] He and Hamilton's second, Nathaniel Pendleton loaded the pistols, and were present when Burr fatally shot Hamilton.^[13]

Van Ness was nominated by President James Madison on May 25, 1812, to the United States District Court for the District of New York, to a new seat authorized by 2 Stat. 719.^[1] He was confirmed by the United States Senate on May 26, 1812, and received his commission on May 27, 1812.^[1] Van Ness was reassigned by operation of law to the United States District Court for the Southern District of New York on April 9, 1814, to a new seat authorized by 3 Stat. 120.^[1][14] His service terminated on September 6, 1826, due to his death in New York City.^[1] He was interred in Brooklyn's Green-Wood Cemetery.^[15]

Van Ness was born to Judge Peter Van Ness (1734–1804), a wealthy lawyer and farmer who owned the property in Kinderhook, New York, on which Van Ness constructed a mansion in 1797.^[19] Martin Van Buren later purchased the home and land and renamed the estate Lindenwald. Peter Van Ness is buried on the Lindenwald estate.^[20] Van Ness's brothers included United States Representative and Washington, D.C. Mayor John Peter Van Ness^[21] and Governor of Vermont Cornelius P. Van Ness.^[22] In 1800, Van Ness married Anne McEvers (1767–1829) in Red Hook. They were members of the Dutch Reformed Church, and the parents of five children.^[23]

Van Ness was the author of several political and judicial works, including: Examination of Charges against Aaron Burr (1803); The Laws of New York, with Notes, (with John Woodworth), (2 vols. 1813); Reports of Two Cases in the Prize Court for New York District (1814); and Concise Narrative of Gen. Jackson's First Invasion of Florida (1826).^[24]

Van Ness' role in the Burr–Hamilton duel is referenced in the musical Hamilton as part of the song "The World Was Wide Enough".^[25]