IAAF (International Association of Athletics Federations) sets rules for track and field athletics across the world, including the Olympics
CAS (Court of Arbitration for Sport) settles sports disputes via arbitration. Olypmics disputes must be submitted to CAS. CAS can be overruled in appeal to Supreme Court of Switzerland.
IAAF Policy as of Jun 2019
IAAF policy requires DSD (Disorders of sex development) athletes to reduce testosterone to less than 5 nmol/L for events between 400m and 1 mile.
Most females (including elite female athletes) have low levels of testosterone circulating naturally in their bodies (0.12 to 1.79 nmol/L in blood); while after puberty the normal male range is much higher (7.7 – 29.4 nmol/L) (source)
Jan 1991 - Born
Aug 2009 - IAAF sex-tests Semenya 3 hours before she wins gold in 800m at the World Championships
Mar 2010 - Semenya temporarily denied opportunity to race until IAAF released findings of gender test
Jul 2010 - Semenya cleared
2011 - IAAF enacts policy that restricts permitted levels of testosterone to 10 nmol/L in blood)
Aug 2012 - Semenya win silver in the London Olympics 800m
Nov 2015 - After Anti-doping scandal, Semenya gets gold retroactively for the 2012 Olympics
Apr 2018 - IAAF issues new testosterone rules (see above)
May 2019 - CAS rejects Semenya's appeal
Jun 2019 - Swiss supreme federal court orders IAAF to suspend testosterone regulations.
1978 - Born
2012 - Transitions to female
2017 - Hubbard wins gold medal in weightlifting's Australian International