The World Para Swimming Classification Rules and Regulations - version September 2015 and the Guidelines for Hosting World Para Swimming International Classification Evaluations can be found in the pdf link below
IPC RULES and Regulations
FINA RULES and Regulations
Swimming was one of the first organised sports for people with disabilities, and was contested at the first Summer Paralympics in 1960.
Both the rules for the sport and approval of classifications were the responsibility of the Fédération International de Natation Amateur (FINA) until 1992, when the International Paralympic Committee took over the governance of classification. As of 2012, people with visual, physical and intellectual disabilities are eligible to compete in the sport.
The classification system was originally based on medical criteria, but has since moved to one largely based on functional disability to make para-swimming more competitive. The sport is moving towards an evidence-based classification system.