In Michelson v. United States, the Supreme Court ruled on whether a defendant's acquittal in a previous criminal case could be used as evidence of good character in a subsequent trial. The court held that while an acquitted defendant may present evidence of his prior acquittal to show good character, the prosecution may then cross-examine and challenge this claim by questioning the circumstances surrounding said acquittal. This ruling was based on two main considerations: first, that such evidence is relevant to assessing credibility; secondly, it prevents undue prejudice against prosecutors who are not allowed to introduce past convictions unless defendants open up their own character for scrutiny. Therefore, although an accused can use past exoneration as proof of moral standing or reputation during trials, it also opens them up for potential examination about those incidents from prosecuting attorneys.

In the dissenting opinion for Michelson v. United States, Justice Robert H. Jackson disagreed with the majority's decision to allow evidence of a defendant's prior criminal record into court proceedings as character evidence in certain circumstances. He argued that this practice was inherently prejudicial and could unfairly influence jurors against the defendant based on their past actions rather than focusing solely on the crime at hand. Furthermore, he contended that allowing such evidence would essentially force defendants to prove their good character or innocence instead of placing the burden of proof where it belongs - on prosecution to prove guilt beyond reasonable doubt. This shift, according to Justice Jackson, undermines one of our justice system’s fundamental principles: presumption of innocence until proven guilty.