Evidence is used in court to prove the arguments that prosecutors and defendants make. For example, the defendant’s fingerprints on a murder weapon would prove that the defendant had touched the murder weapon. Evidence can only be admitted if it is relevant and meets the jurisdiction’s evidence laws.
4 Types of Evidence In Court
There are strict rules surrounding the types of evidence that may be presented in court to ensure the defendant has a fair trial. Because the jury uses the evidence to reach a verdict, presenting evidence that is irrelevant to the case but makes the defendant unlikeable is not allowed. The court will allow the following four types of evidence, though the court may give more weight to certain types over others.
Physical Evidence
Physical evidence is an item involved in the case, like a murder weapon, clothes, blood samples, or other physical objects. The court often gives a lot of weight to physical evidence as long as it follows the rules of the chain of custody and the lawyer admitting the evidence follows a process called “laying a foundation.” Laying the foundation is when witness testimony establishes the relevance of the evidence. Witnesses like police officers or scientists who analyzed the evidence might have to testify to the chain of custody procedures they followed.
Physical evidence can only be used if it is relevant to the case. For example, a hoodie that was found near the crime scene with the victim’s blood on it and the defendant’s DNA on the inside.
Documentary Evidence
Documentary evidence is presenting a paper that proves or refutes allegations by other parties at trial. This type of evidence can take many forms:
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- Text or email chains
- Financial statements
- Contracts
- Newspaper articles
- Letters
Each jurisdiction will have guidelines for how to authenticate and present documentary evidence.
Demonstrative Evidence
Demonstrative evidence is a visual aid that accompanies witness testimony. Examples could be charts, crime scene diagrams, weather reports, graphs, or maps. The witnesses will use demonstrative evidence to help the jury to better understand their testimony. Demonstrative evidence can also be used during cross-examination of witnesses.
Testimonial Evidence
Testimonial evidence is a witness giving a statement about things they witnessed or heard related to the crime. The witness will be sworn in under oath to ensure they are telling the truth.
Is All Evidence Admissible?
No. Each jurisdiction will have evidence admissibility guidelines, but in general, evidence has to meet the following requirements:
- Authentic – The evidence must be authentic and meet any tests the court requires to authenticate it. For physical evidence, this may be providing the chain of custody.
- Probative – The evidence must prove or disprove something.
- Low prejudicial or shock value – Evidence that is shocking or will create prejudice against a party cannot be presented if it has no other value. The court will weigh the shock value against what the evidence adds to the case in probative value.
Legal Grey Areas For Evidence
There are some grey areas that are left up to the judge’s discretion surrounding the probative value of evidence vs the prejudicial value. For example, previous crimes committed by the defendant would create prejudice for the jury but may be necessary for the plaintiff or prosecutor to mention when proving a charge or sentencing request.
A judge will examine each piece of evidence to decide if the prejudicial value outweighs the probative value. They may allow certain pieces of evidence to be admitted but not others. The defendant’s lawyer can object to the admission of certain evidence and present arguments why they believe the prejudicial value is too high. Often, the judge will consider these arguments and any counterarguments the other parties may present to the probative value of the evidence.