Despite headlines suggesting Tour de France winner Floyd Landis tested positive for a banned substance, the truth of the cyclist's guilt or innocence is not immediately clear, says a Duke University expert in sports law.
"When people are saying Landis has tested positive for using testosterone, that is inaccurate and potentially misleading," said law professor Paul Haagen.
"Although everyone wants an instant answer, it probably is going to take a little bit of time to get one because unlike with some of the steroids or other drugs, you don't have a direct test for testosterone," Haagen said. "So far, the first test result only shows an imbalance in a naturally occurring hormone."
Haagen pointed to another factor that complicates the interpretation of the sample results, which were taken from Landis near the end of the race.
"For athletes looking to gain an advantage, testosterone is normally ingested during training to speed the rebuilding of muscles," he said. "I am not aware of anything that would actually suggest that testosterone improves competition performance, in contrast to a drug like EPO (erythropoietin), which clearly does."
Haagen said an athlete taking testosterone during training would typically show elevated levels of testosterone in samples taken at the beginning of a race.
"We're in a position of some uncertainty and doubt," he said.