Criminal evidence is any physical or verbal evidence that is presented for the purpose of proving a crime. This evidence can take many different forms and may also be introduced by the defendant to prove that they are not guilty. It is illegal to attempt to hide any of this evidence, an action that is known as spoilation of evidence, from the other side or from the authorities. In any criminal trial, the burden is on the prosecution to prove that the defendant committed the crime.
Criminal evidence may basically come in two different forms, verbal or physical. Examples of verbal evidence may include:
- Confessions made by the defendant
- Testimony offered by witnesses and expert witnesses
- Text of documents such as a search warrant or other files
- Spoken evidence obtained through a wiretap or other similar technology
Physical evidence is any tangible evidence and is usually presented as an exhibit. Examples can include:
- Weapons or other instruments used to commit a crime
- Illegal contraband such as drugs, drug money, and drug paraphernalia
- DNA, blood, or bodily samples
- Photographs or video footage
- Demonstrative evidence
- Footprints or other types of tracks
- Scientific and forensic evidence
All criminal evidence may be further classified into either direct or circumstantial evidence. Direct evidence supplies the prosecution with information that is true “beyond a reasonable doubt” (for example, a videotape showing the defendant injuring the victim). Circumstantial evidence does not prove a theory but rather only suggests proof in support of the theory (for example, a knife that fits the description of witness testimony).
For evidence to be admissible in court, the evidence must be logically relevant, material, and competent. For evidence to be relevant, it must have a reasonable tendency to help prove or disprove a fact. The evidence does not have to make a fact certain, but rather make a fact that is of consequence more or less probable than it would be without the evidence.
Even if evidence is relevant, the evidence must be legally relevant meaning that the probative value of the evidence must not be substantially outweighed by the dangers of unfair prejudice, confusion of jury, waste of time, misleading of the jury.
Although most evidence is permitted for use at trial, the rules, such as the hearsay evidence rule, prevent certain types of evidence from being admissible at trial. These rules are even stronger in criminal cases because the Constitution guarantees criminal defendants certain rights. However, most of these rules have special exceptions, and are subject to change from state to state, so check with an attorney before heading to court.
The following types of evidence are not permitted against criminal defendants:
- Out of Court Testimony – The Sixth Amendment gives criminal defendants the right to confront their accusers.
- Character Evidence – Prosecutors cannot use evidence of a defendant’s personality to prove that the defendant committed the crime unless the defendant raises the issue first.
- Plea Bargaining – Statements made during plea bargains cannot be used against the defendant at trial.
- Self-Incrimination – Defendants have the right not to take the stand during trial because the prosecutor’s cross examination could lead the defendant to incriminate him or herself.
The presentation of evidence in a criminal case can have powerful effects on the verdict. For example, if evidence was illegally obtained by the police, it cannot be used in court. Thus, it may be necessary to work with a criminal lawyer if you are facing criminal charges. An attorney can help you review the evidence so that you obtain your full rights under the law.