For Olympic gold medalist Gil Roberts, a kiss was more than a kiss.

The Court of Arbitration for Sport on Thursday sided with Roberts' defense that he tested positive for a banned substance due to passionate kissing.

Roberts was suspended last May for a positive drug test. That decision was reversed in July 2017 by an arbitrator, who upheld the sprinter's defense that the drug was in his system due to frequent and passionate kissing of his girlfriend.

In Thursday's decision the CAS arbitrators agreed, ruling against the World Anti-Doping Agency's appeal, deeming that it was more likely than not "that the presence of probenecid in the athlete's system resulted from kissing his girlfriend."

"There could have been tongue kissing, but it was more that she kissed me so soon after taking the medicine," Roberts told The New York Times on Thursday.

A professional since 2009, Roberts was part of the United States' 4x400 relay team that won gold at the 2016 Rio Olympics.

In March, he tested positive for a drug called probenecid, and in May, the United States Anti-Doping Agency said Roberts' B sample also tested positive for the masking agent.

The case went to an arbitrator in June.

As part of the evidence, the stepfather of Roberts' girlfriend said she was in India a few weeks before the March test and came down with a sinus infection. A local "chemist" there directed her to take one capsule of Moxylong per day for a period of two weeks.

The woman, Alex Salazar, continued to take the medicine when she returned to the U.S., breaking the capsule apart and pouring its contents into her mouth before swallowing with water. USADA said the sides told the arbitrator that Roberts and Salazar "kissed frequently and passionately" when they were together, including on March 24, when Roberts was initially tested. Salazar ingested the medicine that afternoon, the two kissed after that, and the doping officer arrived three hours later.

Salazar was unsure how many times they kissed between when she took the medicine and when Roberts was tested.

Roberts testified then that he did not know that kissing his girlfriend could lead to a positive test, nor did he know she was taking Moxylong.

"Thus, for Roberts, it must have been like lightning out of a clear blue sky for him to learn that by kissing his girlfriend this time that he was exposing himself to a prohibited substance. Roberts has met his burden of proof," USADA said in its ruling in July.

Similarly, tennis player Richard Gasquet escaped a lengthy doping ban in 2009 when the International Tennis Federation's tribunal panel ruled that he inadvertently took cocaine by kissing a woman in a nightclub.

Gasquet convinced the independent anti-doping tribunal that he ingested cocaine with the kiss with the woman he had just met. The tribunal panel of three lawyers said Gasquet consumed no more than "a grain of salt" of the drug, and a long ban would be an injustice in a case that was "unusual to the point of being probably unique."

Another athlete, Canadian pole-vaulter Shawn Barber, tested positive for cocaine before the Rio Olympics in 2016 following a tryst with a woman he met on Craigslist. The 2015 world champion was permitted to compete in Brazil after it was determined he inadvertently ingested trace amounts of the banned substance through kissing.