May was born in Washington, D.C., on February 13, 1816. He was a son of Dr. Frederick May (1773–1847) and Juliana Mathilda (née Slacum) May (1793–1822). His siblings included John Frederick May, William May, Julia Matilda (née May) Oelrichs (mother of Hermann Oelrichs, Charles May Oelrichs and Lucie Oelrichs Jay), Laura (née May) Wise (the wife of Gen. George D. Wise), and Julian S. May. His father, who was born in Boston, was a physician who spent nearly the last fifty years of his life practicing in Washington.[1][2]
His paternal grandparents were Abigail (née May) May and Col. John May, who participated in the Boston Tea Party and became a prominent soldier in the American Revolutionary War.[3]
In 1850, May was sent by President Franklin Pierce to Mexico to investigate claims under the United States' treaty of peace with Mexico. He moved to Baltimore, Maryland. In 1852, May was elected as a Democrat to the Thirty-third Congress, serving one term from March 4, 1853 to March 3, 1855. He was an unsuccessful candidate for reelection in 1854 to the Thirty-fourth Congress, but was elected as a Unionist to the Thirty-seventh Congress, serving from March 4, 1861 to March 3, 1863.
May sat in the special session of Congress held in summer 1861 after the outbreak of the Civil War.[4] In September 1861 May was arrested without charges or recourse to habeas corpus on suspicion of treason and held in Fort Lafayette.[5][6] (Lincoln had unilaterally suspended habeas in Maryland in spring 1861, a move ruled unconstitutional without Congressional authorization in June 1861 by Supreme Court Chief Justice Roger Taney in ex parte Merryman, a disputed ruling which Lincoln disregarded.) May was eventually released—no charges were ever brought or evidence produced—and returned to his seat in Congress in December 1861. In March 1862 he introduced a bill requiring the federal government to either indict by grand jury or release all other "political prisoners" held indefinitely without recourse to habeas.[7] The provisions of May's bill were included in the March 1863 Habeas Corpus Act in which Congress finally authorized Lincoln to suspend habeas corpus, but required actual indictments for suspected traitors.[8] The "political prisoners" affected included Baltimore newspaper editor, and vocal Lincoln critic, Frank Key Howard, who had been a co-prisoner with May, and was also a grand-nephew of Chief Justice Taney's wife Anne Key, (Francis Scott Key's sister).[9]
On November 29, 1845 May was married to Henrietta de Courcy (1820–1919) in Chester, Maryland.[11] She was the daughter of William Henry de Courcy and Eliza Bond (née Rozier) de Courcy.[12] Together, they were the parents of:[13]
Henry May (1854–1936), who married Isabel Theresa Coleman of New Jersey in 1881.[22]
George May (1855–1931), who became a prominent Baltimore banker with Alex. Brown & Sons.[23]
Julia May (1859–1954), who married George Albert Bech, a son of Edward Bech, in 1887.[24] After Bech's death in 1890,[25] she married William Babcock and moved to California.[26]
