In law, rules of evidence govern the types of evidence that are admissible in a legal proceeding. Types of legal evidence include testimony, documentary evidence, and physical evidence. The parts of a legal case which are not in controversy are known, in general, as the "facts of the case." Beyond any facts that are undisputed, a judge or jury is usually tasked with being a trier of fact for the other issues of a case. Evidence and rules are used to decide questions of fact that are disputed, some of which may be determined by the legal burden of proof relevant to the case. Evidence in certain cases (e.g. capital crimes) must be more compelling than in other situations (e.g. minor civil disputes), which drastically affects the quality and quantity of evidence necessary to decide a case.
Scientific evidence consists of observations and experimental results that serve to support, refute, or modify a scientific hypothesis or theory, when collected and interpreted in accordance with the scientific method.
The burden of proof is the obligation of a party in an argument or dispute to provide sufficient evidence to shift the other party's or a third party's belief from their initial position. The burden of proof must be fulfilled by both establishing confirming evidence and negating oppositional evidence. Conclusions drawn from evidence may be subject to criticism based on a perceived failure to fulfill the burden of proof.
Two principal considerations are:
The latter question depends on the nature of the point under contention and determines the quantity and quality of evidence required to meet the burden of proof.
In a criminal trial in the United States, for example, the prosecution carries the burden of proof since the defendant is presumed innocent until proven guilty beyond a reasonable doubt. Similarly, in most civil procedures, the plaintiff carries the burden of proof and must convince a judge or jury that the preponderance of the evidence is on their side. Other legal standards of proof include "reasonable suspicion", "probable cause" (as for arrest), "prima facie evidence", "credible evidence", "substantial evidence", and "clear and convincing evidence".