Science was supposed to clinch OJ Simpson's guilt in the criminal trial that entranced both press and public in the United States for ten months in 1995. Prosecutors mistakenly expected the powerful technique of DNA fingerprinting, or `DNA typing', to establish Simpson's presence at the crime scene and to confirm his subsequent flight to his own estate. By acquitting Simpson after less than four hours of deliberation, the jury sensationally rebuffed the prosecutors' expectations. Fifteen months later, it was the mundane evidence of bloody shoeprints, not scientific authority, that prompted a civil judgment against Simpson for the same killings. In exploring science's failure to persuade the first Simpson jury, this paper focuses on the trial as an arena in which visual authority had to be created and defended. Scientific evidence must be seen to be believed; yet, a trial is also a proceeding in which visual authority is deeply contested. The paper suggests that the judge's rôle in constructing authorized lines of sight has not received sufficient attention in legal analysis and procedural reform. In the Simpson trial, as in other cases involving expert witnesses, the judge's uncontested remarks and rulings established at many crucial points whose vision would be authorized as expert, and in what circumstances lay vision could take precedence over expert sight.