The World Boxing Council on August 17 decided not to ban Russian heavyweight title contender Aleksandr Povetkin after he tested positive for the banned substance meldonium.
Povetkin was due to face heavyweight champion Deontay Wilder of the United States in May before it was revealed he had failed a drug test.
The fight was called off and Wilder was allowed to arrange a fight against Chris Arreola in July, which he won.
The council said Povetkin must undergo extra drug testing at his own expense for a year. But he won't be banned, given "the impossibility to scientifically prove that Mr. Povetkin ingested meldonium after January 1 2016," when it became illegal in sport.
If Povetkin tests positive again over the next year, he will be suspended from boxing "indefinitely," the council said.
With Wilder injured and likely unable to fight until 2017, the council ordered Povetkin to fight Canada's Bermane Stiverne for an interim title.
"We won," Povetkin's promoter Andrei Ryabinsky said on Twitter. "Povetkin has been vindicated."
Based on reporting by AP and TASS