The World Anti-Doping Agency has asked the sport's highest court to ban U.S. cyclist Tyler Hamilton for life for doping.
The former Olympic champion was given an eight-year ban last month by the U.S. Anti-Doping Agency after he admitted taking a steroid in an herbal remedy for depression.
It was the 38-year-old Hamilton's second doping offense, which usually triggers a lifetime ban. He has said he would retire from the sport.
The Court of Arbitration for Sport said Thursday that WADA has challenged the American ruling and called for a lifetime sanction.
Hamilton, of Boulder, Colo., served a two-year ban for blood doping that ended in 2007. His time trial gold medal at the 2004 Athens Olympics was clouded by suspicions of blood doping.
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