During the Games, Olympians could be tested anytime, without any advance notice. The antidoping lab used during the London 2012 Olympics was the first ever underwritten by a major pharmaceutical company, Glaxo-SmithKline; it tested 400 samples per day.
WADA also advocates the use of a "biological passport" – a compilation of data that shows each athlete's natural level for certain biological markers and hormones. That way, scientists can monitor those levels for unusual activity. Biological passports played a key role in cycling's doping crackdown.
Other professional sports leagues that follow WADA guidelines include the International Tennis Federation, all arms of the Professional Golfers' Association, the National Hockey League, Major League Soccer, and the English Premier League. The National Basketball Association, Major League Baseball (MLB), the National Collegiate Athletic Association, and the NFL don't follow the WADA code: They conduct their drug testing in-house and hand out much lighter penalties. That opens them up to criticism.