Evidence is information that exists in physical or digital form—such as written agreements and e-mail communications—as well as testimony from witnesses who have personal knowledge of facts relevant to a dispute. Evidence generally must be relevant to be admitted in court and considered by the factfinder (judge or jury) in resolving a lawsuit. And some forms of evidence, such as expert witness testimony, must be shown to be sufficiently reliable (as determined by the judge) to be admitted in evidence.

In Tennessee, as in other jurisdictions, evidence must be relevant to be admissible in court. Relevance is determined by whether the evidence makes a fact more or less probable than it would be without the evidence, and whether the fact is of consequence in determining the action. Both physical and digital forms of evidence, such as written agreements and email communications, can be admitted if they meet this relevance criterion. Additionally, witness testimony is admissible if the witness has personal knowledge of the facts at issue. Expert witness testimony is subject to a reliability standard, which requires the judge to determine whether the testimony is based on sufficient facts or data, is the product of reliable principles and methods, and whether the expert has reliably applied the principles and methods to the facts of the case. This reliability standard is in line with the federal Daubert standard, which Tennessee has adopted. The rules governing the admissibility of evidence in Tennessee are primarily found in the Tennessee Rules of Evidence.