Weight of Evidence

Measure of credible proof on one side of a dispute as compared with the credible proof on the other, particularly the PROBATIVE evidence considered by a judge or jury during a trial.

The trier of fact in a civil or criminal trial, whether a judge or a jury, must review the evidence presented, evaluate it, and determine if it meets the standard of proof. If it meets this standard, the trier of fact must return a verdict in favor of the plaintiff in a civil suit and must convict a defendant in a criminal trial. If the evidence does not meet the standard of proof, the trier of fact must find for the defendant in a civil or criminal case. These decisions are based on the concept of the "weight of evidence."

The weight of evidence is based on the believability or persuasiveness of evidence. The probative value (tending to convince a person of the truth of some proposition) of evidence does not necessarily turn on the number of witnesses called, but rather the persuasiveness of their testimony. For example, a witness may give uncorroborated but apparently honest and sincere testimony that commands belief, even though several witnesses of apparent respectability may contradict her. The question for the jury is not which side has more witnesses, but what testimony they believe.

Particular evidence has different weight in inducing belief with respect to the facts and circumstances to be proved. Evidence that is indefinite, vague, or improbable will be given less weight than evidence that is direct and unrefuted. For example, a criminal defendant's testimony that he had never been at the scene of a crime would be given little weight if his fingerprints were found at the crime scene and witnesses testify they saw him at the scene. Similarly, evidence given by a witness who testifies from personal observation is of greater weight than evidence offered by a witness who is testifying from general knowledge alone.

In a civil trial, the plaintiff's BURDEN OF PROOF is the PREPONDERANCE OF THE EVIDENCE standard, which means that the plaintiff must convince the trier of fact that the evidence in support of his case outweighs the evidence offered by the defendant to oppose it. In contrast, criminal trials require that the weight of evidence proving a defendant's guilt must be BEYOND A REASONABLE DOUBT.

In a number of jurisdictions, judges are prohibited from instructing juries on the weight to be given to evidence. In other states, the judge is permitted to give a balanced and fair assessment of the weight she believes should be ascribed to the evidence. All jurisdictions prohibit the judge from instructing the jury on what weight is to be given to the testimony of any witness or class of witnesses. The judge may not state that any particular piece of admissible evidence is or is not entitled to receive weight or consideration from the jury. The judge is also forbidden either to aid a jury or to infringe upon its role in weighing the evidence or in deciding upon the facts. In addition, the judge, in giving her instructions to the jury, has no right to prescribe the order and manner in which the evidence should be examined and weighed by the jury, or to tell the jurors how they shall consider any evidence that has been received by the court.