New Zealand-born United States winger James Paterson has been confirmed as the player who failed a drugs test during the Rugby World Cup.
The International Rugby Board says Paterson, a former Highlander, has been handed a four-month ban after testing positive for the painkiller oxycodone.
He was provisionally suspended on October 13 and can return to rugby on February 13.
World anti-doping agency WADA classifies oxycodone as a narcotic and it is prohibited in competition only.
The IRB says the painkiller was administered to allow Paterson to take the field for the US in their final pool fixture against Italy in Nelson on September 27.
The 24-year-old had suffered a shoulder injury against Russia 12 days earlier.
IRB anti-doping manager Tim Ricketts says the case was unfortunate and could have been avoided by referring to the WADA prohibited list, which was available to all teams and players at the tournament.
USA Rugby chief executive Nigel Melville offered an apology to Paterson, saying his character and integrity shouldn't be questioned.
At the time of testing, Paterson disclosed the medications he was using, including oxycodone.
Melville said trust was at the centre of the issue and Paterson was acting on the trust he had in the medical staff.
Born in Christchurch, Paterson has played provincial rugby for Canterbury and Southland.
He was also part of the Highlanders' Super rugby campaigns in 2010 and 2011, but his name was missing when the New Zealand franchises named their squads for 2012.