What is Weight of Evidence?

Felicia Dye

Weight of evidence is a legal term used when gauging the sufficiency of proof that is presented in a legal dispute. For this method of analysis to work, it is necessary to consider the evidence from the opposing parties and to compare them. This comparison should lead to a decision of which party appears to have the strongest case. The party that lacks the weight of evidence, therefore, should be the party the court rules against.

In a criminal investigation, some pieces of evidence may be given a higher form than others.
In a criminal investigation, some pieces of evidence may be given a higher form than others.

In a court case, there are at least two parties. The prosecution generally is supposed to bear the burden of proving the guilt of the defendant. Both parties, however, are likely to submit evidence to support their claims. This could lead a person to falsely assume that the party that presents the most evidence will be the one whose case has the greatest weight and thereby the winner.

One reason that more evidence does not necessarily result in a favorable outcome is that some evidence is not necessarily true, some will be deemed inadmissible, and sometimes verification of proof is unavailable to determine the truth of the evidence. It is important to remember that evidence is merely material, sometimes oral and sometimes physical, which is provided in an attempt to convince the trier of fact, which is generally a judge, jury, or magistrate.

It is the legal responsibility of these individuals to assess the evidence provided and to determine what is relevant and what is believable. Another assumption that should not be made when trying to understand the principles of weight of evidence is that all evidence must be verified. Sometimes verification is not possible but the trier of fact may still find the evidence believable. This means that it will count in favor of the party that presented it.

Although the jury may find some evidence believable even when it lacks concrete support, this does not mean it is given a higher value than evidence that can be confirmed. When considering weight of evidence, some items can weigh more heavily than others. For example, a photograph may carry heavier weight than an unverified oral testimony although the trier of fact is inclined to believe both. One of the difficulties of being a trier of fact is that each side may have some evidence that weighs in favor of their arguments. The side whose overall presentation of evidence is most convincing can be said to possess the weight of evidence and, therefore, should win the case.

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Discussion Comments


If I'm on the jury, I am likely to put more weight on the evidence given by an eyewitness. All the expert testimony and the scientific reports are great, but I am more impressed by a believable person who saw what happened.


@mobilian - I agree with most of what you said about the value of DNA evidence. This type of evidence can go a long way toward giving a defendant or a prosecutor the weight of evidence. And I read those articles about DNA evidence freeing wrongly convicted people, too.

However, I have also read articles and seen news shows about the people who do the DNA testing. Some of them do sloppy jobs and some of them just lie. In the end the scientific evidence is only as good as the people doing the testing.


@Laotionne - I disagree with you about the value of scientific evidence in the courtroom. If DNA testing had been around longer we would have less innocent men and women in prisons. Hardly a day goes by that you don't hear about someone who has spent years in prison being freed because DNA evidence showed he or she didn't do the crime he or she was sent to prison for committing.

I don't care how big of an expert you are you can't change a person's DNA.The weight of evidence is always in favor of whichever side is supported by the DNA evidence.


I don't know what to think about scientific evidence. I watch court TV shows and real life mysteries and crime shows. Both sides, the defense and the prosecution, always have some type of experts testifying in support of their cases. What makes me have doubt is that the two experts can look at the same evidence and come up with totally different opinions and findings depending on whether they are for the prosecution or the defense.

What good do the experts really do? If I were in charge, I would say the experts cancel one another out so let's not waste time hearing from either of them.

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