Earlier this year, the Olympic sprinter tested positive for probonecid, a masking agent that is banned by the U.S. Anti-Doping Agency.
Although he was cleared at the hearing on 20 June, the detail from the arbitration has only just been released by Usada.
A kiss is just a kiss, unless, apparently, that kiss is followed by a doping test.
An independent arbitrator ruled in favor of Roberts, saying the USADA failed to prove he took any banned substance on objective and pointed to his previously spotless record.More news: Jose Mourinho Reveals How and Why Potential Alvaro Morata Deal Fell Apart
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.
"This arbitrator is persuaded by Dr. Kintz' testimony that bits of the probenecid that remained in her mouth after she took her medicine could and did move to his mouth through their frequent passionate kissing".
A doctor serving as an expert witness for Roberts testified that his level of probenecid was much lower than it would have been had he taken an entire pill and was not enough to mask any drugs in his system.
USADA accepted the ruling on June 24, rescinding calls to ban the athlete, who went on to compete at the USATF Outdoor Championships that were now underway. 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.
"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". Canadian pole vaulter Shawn Barber blamed his positive drug test before the 2016 Olympics on kissing a woman who had consumed cocaine, and in 2009, tennis player Richard Gasquet said he was partying and kissed a woman with cocaine on her lips.