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 Texas, as in other states, the admissibility of evidence in a criminal prosecution is governed by both state and federal law. Under the Fourth Amendment of the U.S. Constitution, evidence must generally be obtained legally for it to be admissible in court. This means that law enforcement officers are typically required to obtain a search warrant before conducting a search that would intrude upon an individual's reasonable expectation of privacy. However, there are several exceptions to this requirement, such as when an individual gives consent to a search, when evidence is in plain view, during a search incident to a lawful arrest, or in exigent circumstances where there is no time to obtain a warrant. Additionally, the evidence must be relevant to the case, meaning it must have a tendency to make a fact of consequence more or less probable than it would be without the evidence. It must also be reliable, which means it must be trustworthy and credible. Texas courts also adhere to the Texas Rules of Evidence, which provide specific guidelines on the admissibility of evidence in criminal proceedings.
