For evidence to be admissible in a criminal prosecution it generally must have been obtained legally—with a search warrant, or based on an exception to the search warrant requirement, such as consent to search—and be relevant and reliable.
In South Dakota, as in other states, evidence must be obtained legally to be admissible in a criminal prosecution. This means that law enforcement officers typically need to obtain a search warrant before conducting a search that would otherwise violate an individual's reasonable expectation of privacy. However, there are several exceptions to the search warrant requirement, such as when an individual gives consent to a search, when evidence is in plain view, during exigent circumstances, or when the search is incident to a lawful arrest. Additionally, for evidence to be admissible, it must be relevant to the case, meaning it must have a tendency to make a fact more or less probable than it would be without the evidence. The evidence must also be reliable, which generally means that it must be trustworthy and its integrity has not been compromised. South Dakota follows the rules of evidence which are similar to the Federal Rules of Evidence in determining the admissibility of evidence in criminal proceedings.