Quote from the article:

“The state established the redress mechanism after the Kumamoto District Court handed down a landmark ruling in 2001 calling the state’s segregation policy against leprosy patients unconstitutional. A law that decreed patients must be quarantined to prevent the disease’s spread was abolished in April 1996.”

http://www.japantimes.co.jp/news/2016/03/15/national/crime-legal/former-leprosy-patients-japan-urged-file-state-compensation-final-deadline-nears/#.VugYX8dq0pZ