The case involves María Guadalupe González Romero, a Mexican race-walker, who appealed a decision by the International Association of Athletics Federations (IAAF) regarding an anti-doping rule violation. The dispute arose after an out-of-competition test on October 17, 2018, revealed the presence of Epitrenbolone, a metabolite of Trenbolone, a prohibited substance. The IAAF Disciplinary Tribunal found her guilty of an anti-doping violation and imposed a four-year ban, disqualifying her results from the date of the test. González Romero argued that the substance entered her system through contaminated meat, but the tribunal deemed her evidence unconvincing and contradictory, concluding she failed to prove the violation was unintentional. The Court of Arbitration for Sport (CAS) addressed several key legal issues, ruling that by signing a Doping Control Form, an athlete is generally estopped from later claiming violations of testing procedures unless there is evidence of fraud or manipulation. The panel found no conflict of interest merely because the Doping Control Officer and chaperone were married, as long as they were independent from the athlete. It emphasized that only significant departures from testing standards could invalidate an adverse finding, balancing athletes' rights with the broader interest in preventing doping violations based on minor procedural issues. Regarding intent, CAS upheld the tribunal's decision, stating that González Romero failed to provide sufficient evidence to demonstrate how the substance entered her body. Mere allegations of contaminated meat consumption were insufficient without concrete proof. The panel affirmed the four-year ban, crediting her provisional suspension period. The ruling underscores the strict liability principle in anti-doping regulations, requiring athletes to prove unintentional violations with credible evidence. The case highlights the challenges athletes face in contesting doping charges and the high evidentiary standards required to overturn sanctions. The CAS Panel rejected the reliability of a polygraph test submitted by González Romero, citing previous rulings that deemed such tests inadmissible. Her case was contrasted with another where an athlete successfully proved contamination, but the Panel noted significant differences, as González Romero failed to provide credible evidence like receipts, records, or expert testimony. She admitted to fabricating evidence, which severely undermined her credibility. The Panel concluded she did not demonstrate how the substance entered her body or that the violation was unintentional, ruling the ADRV intentional. The mandatory four-year sanction was upheld, and all competitive results obtained between October 17, 2018, and November 16, 2018, were disqualified, including forfeiture of titles, awards, medals, points, and prize money. The appeal was dismissed, and the original decision was confirmed in its entirety, reaffirming the strict liability principle in anti-doping regulations and the importance of credible evidence in such cases.