JOIN USSwimming's governing body FINA banned Napoleon for three months, starting Aug 20, after he tested positive for formoterol, blamed by Swimming Australia on a wrongly-labelled asthma inhaler.
But the Court of Arbitration for Sport (CAS) said in a statement on Tuesday that it had partially upheld an appeal from Napoleon and had moved the start of the ban back to June, making him eligible for the Oct 3-14 Commonwealth Games in New Delhi.
He was left out of the team named to compete in New Delhi after receiving the original ban.
"Ryan Napoleon is sanctioned with a three-month period of ineligibility commencing on 15 June, 2010," said the Lausanne-based tribunal.
"All competitive results obtained by Ryan Napoleon from 16 November 2009 up to and including 28 January 2010 shall be disqualified, with all of the resulting consequences including forfeiture of any medals, points and prizes."
Napoleon, who tested positive for formoterol on November 16, had qualified for the 400 and 1500 metres freestyle events.Swimming Australia did not immediately return calls as to whether he would be added to the team.
They said at the time that Napoleon, who has been taking asthma medication for 20 years, was given an incorrectly labelled inhaler containing the substance by a pharmacist.