The Horton Law legalized boxing in the state of New York from 1896-1900. It had been signed into law by the governor April 17, 1896, and became effective September 1, 1896. It was repealed by the Lewis Law, and officially expired August 31, 1900. (Others say September 1.)
New York had legislatively criminalized "prizefighting" in 1859, and made it a misdemeanor to engage in a "prizefight," to arrange a "prizefight," or help a fighter train for a "prizefight." The Horton law expanded the definition of this misdemeanor to include "public or private sparring exhibition[s], with or without gloves, within the state, at which an admission fee is charged or received... provided, however, that sparring exhibitions with gloves of not less than five ounces each in weight may be held by a domestic incorporated athletic association in a building leased by it for athletic purposes only for at least one year, or in a building owned and occupied by such association." NY Laws, 1896, Ch. 301, Sec. 458. That latter language gave rise to many "athletic associations" like the Coney Island Athletic Club and Lennox Athletic Club, which promoted "sparring exhibitions for points." (Some jurisdictions made a distinction between illegal prizefights and permissible "boxing contests.")
It has been said that the Kid McCoy vs. James J. Corbett bout at Madison Square Garden was the final bout conducted under the Horton Law. It was also reported that this bout, among others, caused the repeal of the Horton Law. 
Some editions of the Ring Record Book incorrectly stated that the Horton Law permitted fights to be conducted in New York State without any limit to the number of rounds to be fought and permitted decisions by referees and the posting of forfeits and side bets.