The case of United States v. Leonard Cotton et al., 2001, involved seven defendants who were charged with various drug-related crimes. The main issue in the case was whether a police officer's reliance on a search warrant that turned out to be invalid could still provide evidence for prosecution under the "good faith" exception to the exclusionary rule, which generally prohibits illegally obtained evidence from being used in court. The Supreme Court ruled that even though there had been an error made by a lower court judge when issuing the search warrant, it did not necessarily mean that all resulting evidence should be excluded if law enforcement acted in good faith and relied upon what they believed was a valid warrant at the time of their actions. Therefore, despite some procedural errors during issuance of warrants, as long as officers act within reasonable belief of legality (i.e., 'in good faith'), any resultant evidence can still be admissible.

The dissenting opinion in the case of United States v. Leonard Cotton et al., argued that the majority's decision to uphold the convictions was a departure from established legal precedent regarding DNA evidence and its admissibility in court. The dissenting justices believed that there were significant issues with how DNA evidence was collected, stored, and analyzed in this case which could have potentially led to false positives or contamination. They also expressed concerns about whether all defendants had access to adequate defense resources for challenging such complex scientific evidence. Furthermore, they disagreed with the majority's conclusion that any errors made during trial were harmless beyond a reasonable doubt given these potential problems with the DNA evidence used against them.