Caster Semenya, the world and Olympic 800 meters champion, is fighting "unfair" regulations that hinder certain female athletes.The International Association of Athletics Federations brought in controversial new rules in April that mean some women with high natural testosterone levels could be excluded from middle-distance races.Semenya, a two-time Olympic and three-time world champion, is the highest-profile athlete expected to be impacted by the rules that divide medical opinion.The South African's lawyers, Norton Rose Fulbright, which has offices in London, issued a statement on Monday saying the athlete would "file the legal challenge to ensure, safeguard and protect the rights of all women on the basis the regulations are irrational, unjustifiable, and in violation of the IAAF Constitution (based in Monaco), the Olympic Charter, the laws of Monaco, the laws of jurisdiction in which international competitions are held, and of universally recognized human rights."Caster Semenya contends the regulations are objectionable on numerous grounds, including that they compel women with no prior health complaints to undergo medical interventions to lower their testosterone levels," the statement added.The IAAF argues that women with unusually high levels have a competitive advantage over their rivals and intends, from Nov. 1, to limit entry to all international events from 400 meters through the mile to females with testosterone levels below a specified level.Women with elevated testosterone must reduce their level for "six months (e.g., by use of hormonal contraceptives)" before being eligible to run, and maintain that lowered level.Semenya faces taking daily medication or start racing at 5,000 meters. Without the new rules, she would likely defend her 800 world title in Doha, Qatar, next year.She also took bronze in the 1,500 at the 2017 world championships in London.Testosterone is a naturally produced steroid that helps maintain muscle mass, and production of oxygen-carrying red blood cells. For male athletes, anti-doping rules require further study for potential abuse if the ratio of testosterone to epitestosterone in a urine sample is above a specified level.Semenya's case is going through the Court of Arbitration for Sport.