Pogba's four-year ban imposed by an Italian anti-doping tribunal last year threatened to end the career of the 31-year-old France and Juventus midfielder in one of soccer's highest-profile doping cases.
Instead, Pogba can start playing again in March after three CAS judges cut his ban to 18 months in a verdict revealed on Friday.
His positive test last year for DHEA, a steroid precursor, "was not intentional and was the result of erroneously taking a supplement prescribed to him by a medical doctor in Florida," the court said in a statement released Monday giving the first details about the ruling.
The former Manchester United midfielder "had been given assurances that the medical doctor, who had claimed to treat several high-level US and international athletes, was knowledgeable and would be mindful of Mr Pogba's anti-doping obligations," CAS said.
Pogba was "not without fault and that, as a professional football player, he should have paid greater care in the circumstances," the court said.
The Italian tribunal argued the player had been reckless, the court said, but that evidence, including from expert witnesses at the Juventus star's appeal hearing, supported his case.
Still, the judges did not meet the request from Pogba's lawyers for a one-year ban that would have let him return to soccer immediately.
CAS said the full document detailing the judges' reason has not yet been provided to the parties and therefore gave a limited explanation Monday of the verdict.
Pogba is allowed to train with Juventus from January, though the Italian club has been publicly unenthusiastic about his return.
