The Nigerian hurdler Tobi Amusan was found not guilty of doping violations, but the Athletics Integrity Unit (AIU) has filed an appeal against the original judgment.
The anti-doping authorities announced late last week that they had filed an appeal with the Court of Arbitration for Sport.
Amusan was provisionally suspended for failing three tests within a 12-month period.
The punishment was lifted by the appeals tribunal, allowing the Nigerian to compete in the global championships this past summer, where she ultimately placed sixth.
The 26-year-old could face a suspension of a year or more if proven guilty.
Last weekend, Amusan won the Diamond League championship for the third year in a row.
