In the Claassen v. United States case of 1891, the U.S Supreme Court ruled that a defendant could not be convicted based on uncorroborated confessions alone. The case involved Mr. Claassen who was charged with embezzlement while serving as an officer in a national bank and had confessed to his crime during trial proceedings. However, there was no other evidence presented by the prosecution to support this charge beyond his confession. The court held that although confessions are admissible as evidence, they cannot be used solely for conviction unless supported by additional independent proof or corroborating circumstances which authenticate its accuracy and reliability.

In the dissenting opinion for Claassen v. United States, Justice Lamar disagreed with the majority's decision to uphold Claassen's conviction. He argued that there was a lack of evidence proving beyond reasonable doubt that Claassen had committed fraud or intended to defraud anyone. The only proof presented by the prosecution was an irregularity in bookkeeping which could have been due to error rather than fraudulent intent. Furthermore, he criticized the trial court judge for instructing jurors they could infer guilt from mere suspicion and circumstantial evidence without direct proof of wrongdoing - a standard he believed violated defendant’s rights under U.S law requiring clear and convincing evidence of guilt in criminal cases.