If a case ends in a conviction, the only way to challenge the result is through post-conviction court proceedings. There are three possible remedies:
Imagine you were accused of a crime and your case was dismissed outright due to lack of evidence. Even though the case was dismissed, anyone doing a background check will see that you were arrested and charged with a crime. You were never convicted, but in the eyes of employers or others you may not really have a “clean” legal record.