The Walker Law passed in 1920 was an early New York state law regulating boxing. The law reestablished legal boxing in the state following the three-year ban created by the repeal of the Frawley Law. The law instituted rules that better ensured the safety of combatants and reduced the roughness of the sport. The law limited matches to fifteen rounds, required a physician in attendance, restricted certain aggressive acts such as head-butting, and created a regulatory commission, the New York State Athletic Commission.
The first main event conducted under this new law was the Joe Welling vs. Johnny Dundee bout. Sammy Nable vs. Bobby Hanson possibly was the very first bout ever conducted under the law.
Rosen, Ross. (1995). "Perspective: In the Aftermath of McClellan: Isn't it Time for the Sport of Boxing to Protect Its Participants?". Seton Hall Journal of Sport Law 5, 611–636.