Olympic champion Brianna Rollins has been handed a 12-month ban for missing three drugs tests in a year.
Rollins, 25, claimed gold in the 100-metre hurdles at the Rio Olympics and was world champion in the same event in 2013.
The American was banned for "failing to properly file Whereabouts information", leading to three missed tests in 2016.
"In 2016, Rollins received a Whereabouts Failure from the International Association of Athletics Federations (IAAF) for being unavailable for testing on April 27, 2016," a statement from the U.S. Anti-Doping Agency read.
"Later in the year, Rollins received another Whereabouts Failure from USADA for not being available for testing on September 13, 2016. She then received a third Whereabouts Failure from the IAAF for not being available for testing on September 27, 2016.
"Outside of these Whereabouts Failures, Rollins completed eight out-of-competition tests over the course of 2016.
"However, under the rules of international Olympic sport, including the IAAF Anti-Doping Policy, the United States Olympic Committee National Anti-Doping Policies, and the USADA Protocol for Olympic and Paralympic Movement Testing (the USADA Protocol), all of which have adopted the World Anti-Doping Code, the combination of three Whereabouts Failures within a 12-month period constitutes a rule violation."
Rollins challenged the case before independent arbitrators, but her 12-month ban began on December 19 last year - the date she was notified of a potential rule violation.