One of the biggest storylines of the Beijing Winter Olympics so far has been the saga over Russian figure skater Kamila Valieva, the 15-year-old who has been allowed to continue to compete even though she failed a drug test.

Count American track sprinter Sha’Carri Richardson among those who has been confused by the Court of Arbitration for Sport’s (CAS) decision to let Valieva continue to compete.

Richardson has experience in the matter, as she was barred from the Summer Games in Tokyo last year after she tested positive for marijuana after being considered a gold medal favorite (Valieva helped Russia win gold in the team event and is considered a favorite in individual competition that begins Tuesday and ends Thursday, although the CAS determined no formal medal ceremony will take place after the event).

On Monday, Richardson took to Twitter to express her confusion, and pointed to race as a potential reason for the discrepancy.

“Can we get a solid answer on the difference of her situation and mines? My mother died and I can’t run and was also favored to place top 3. The only difference I see is I’m a black young lady,” Richardson wrote in the first of a series of tweets, adding later, “It’s all in the skin.”

Richardson was one among many Monday who observed that THC, the main psychoactive compound in marijuana, is not performance enhancing, while trimetazidine, the drug Valieva tested positive for, is.

Richardson also took umbrage with the fact that Valieva’s drug test result is just now coming to light when it occurred in December, whereas hers was made public almost immediately last summer.

The CAS’s decision to let Valieva continue to compete was done “to avoid irreparable harm,” the governing body said, but that decision has been roundly criticized, at least in part because it could open the door for more widespread doping in the future.

United States Olympic figure skating legend and NBC Olympics commentator Tara Lipinski wrote on Twitter, “I strongly disagree with this decision. At the end of the day, there was a positive test and there is no question in my mind that she should not be allowed to compete. Regardless of age or timing of the test/results. I believe this will leave a permanent scar on our sport.”

That said, Lipinski did place blame more so on the adults surrounding Valieva as opposed to Valieva herself.

“One more thought. I’ve said this before, she’s just 15. Please keep that in mind. This is a lot for a young person to deal with. I hope that whichever adults faulted her are held ACCOUNTABLE. This is heartbreaking,” Lipinski wrote.