By Sarah Hartley (June 4, 2018, 1:02 PM EDT) -- On April 23, 2018, the International Association of Athletics Federations published its highly controversial new "Eligibility Regulations for The Female Classification: Athletes With Differences of Sex Development" (DSD rules), the latest of several suspect attempts to address whether and under what conditions women with elevated levels of naturally occurring (or endogenous) testosterone will be permitted to compete in women's athletic competitions. The DSD rules are not about doping, but, rather, are about who is afforded the opportunity to compete as a woman, and were adopted in response to earlier litigation before the Court of Arbitration for Sport challenging the sufficiency of the medical science supporting testosterone-based regulations of femininity. Like the earlier rules suspended by the CAS, the DSD rules cannot be justified by the medical science cited by the IAAF. This article explores the background of the DSD rules to shed light on the highly anticipated challenge to the DSD rules we can expect to see this summer....