Gender verification in sports
Gender verification in sports (also sometimes loosely referred to as Sex determination) is the issue of verifying the eligibility of an athlete to compete in a sporting event that is limited to a single gender. The issue arose a number of times in the Olympic games where it was alleged that male athletes attempted to compete as women in order to win, or that a natural intersex competed as a woman. Sex testing began at the 1966 European Track and Field Championships in response to suspicion that several of the best women athletes from Soviet Union and Eastern Europe were actually men.  At the olympics, testing was introduced in 1968 at the Mexico City games. While it arose primarily from the Olympic games, sex determination affects any sporting event. However it appears it most often becomes an issue in elite international competition.
At its introduction, sex determination testing involved the athlete parading naked in front of a panel of gynecologists. Soon this procedure was replaced by laboratory tests (sex chromatin analysis; in particular X chromatin or Barr body analysis) to check whether the athlete has two X chromosomes as is typical in women. By the 1980s, this test was obsolete and IOC replaced it by polymerase chain reaction for the Y-linked gene SRY, starting with the 1992 Winter Olympics. Test results for about one in 500-600 athletes are abnormal. The IAAF, on the other hand, abandoned gender verification altogether starting in 1992, since it was felt that males masquerading as females was unlikely given that the administration of doping tests involved the athlete producing a urine sample under an official's scrutiny.
- Stanisława Walasiewicz, a Polish athlete who won a gold medal in women's 100 m at the 1932 Summer Olympics in Los Angeles, but was found to have partially developed male genitalia in 1980 after her death, and is perhaps the earliest known case.
- Another Polish athlete Ewa Kłobukowska, who won the gold medal in women's 4x100 m relay and the bronze medal in women's 100 m sprint at the 1964 Summer Olympics in Tokyo, is the first athlete to fail a gender test in 1967. She was found to have a rare genetic condition which gave her no advantage over other athletes, but was nonetheless banned from competing in Olympic and professional sports. 
- Eight athletes failed the tests at the 1996 Atlanta Olympics but were all cleared by subsequent physical examinations.
- Indian middle-distance runner Santhi Soundarajan who won the silver medal in 800m at the 2006 Asian Games in Doha, Qatar failed the sex determination test and was stripped of her medal.
The practice has come under fire from those that feel that the testing is humiliating, socially insensitive, and not entirely accurate or effective anyway. The testing is especially difficult and problematic in the case of people who could be considered intersexual. The genetic tests provide potentially inaccurate results and discriminate against women with disorders of sexual development. Genetic anomalies can allow a person to have a male genetic make-up but be physiologically female. 
A commentary published in the Journal of the American Medical Association stated,
"gender verification tests are difficult, expensive, and potentially inaccurate. Furthermore, these tests fail to exclude all potential impostors (eg, some 46,XX males), are discriminatory against women with disorders of sexual development, and may have shattering consequences for athletes who 'fail' a test." 
The article also states:
"Gender verification has long been criticized by geneticists, endocrinologists, and others in the medical community. One major problem was unfairly excluding women who had a birth defect involving gonads and external genitalia (i.e., male pseudohermaphroditism). ...
A second problem is that only women, not men, were stigmatized by gender verification testing. Systematic follow-up was rarely available for female athletes "failing" the test, which often was performed under very public circumstances. Follow-up was crucial because the problem was not male impostors, but rather confusion caused by misunderstanding of male pseudohermaphroditism." 
Sex testing has been done as recently as the Atlanta Olympic games in 1996, but is no longer practiced, having been officially stopped by the International Olympic Committee in 1999. This followed a resolution passed at the 1996 International Olympic Committee (IOC) World Conference on Women and Health "to discontinue the current process of gender verification during the Olympic Games." 
The International Association of Athletics Federations too stopped conducting the tests in 1991. However the Olympic Council of Asia continues the practice.
New rules permit transsexual athletes to compete in the Olympics after having completed sex reassignment surgery, being legally recognized as a member of the target sex, and having undergone two years of hormonal therapy.
- Sisters Tamara and Irina Press won five track and field Olympic gold medals for the Soviet Union and set 26 world records in the 1960s. Their careers suddenly ended when they failed to appear for gender testing at its introduction in 1966. 
- Princess Anne of the United Kingdom was the only female competitor not to have to submit to a sex test at the 1976 Summer Olympics. She was a member of her country's equestrian team.
- R. Peel, "Eve’s Rib - Searching for the Biological Roots of Sex Differences", Crown Publishers, New York, 1994, ISBN 0-517-59298-3
- J.L. Simpson et al, "Gender Verification in the Olympics", JAMA, vol.284, pp. 1568-1569, 2000.
- "Factbox - Gender testing in sport ", Reuters, December 19, 2006
- J.L. Simpson et al, "Gender verification in competitive sports", Sports medicine, vol. 16, pp 305-315 1993.
- K. Mascagni, "World conference on women and sport", Olympic Review XXVI. vol. 12, pp. 23-31, 1996-1997.