Rules of evidence are created to assist in the search for truth and promote a fair process for both parties. Rules of evidence are the most important in common law criminal justice systems which retain the jury system, since it is thought that these rules safeguard against jury's giving inappropriate weight to certain types of evidence.Certain rules of evidence also provide a deterrent effect against prosecutorial or police misconduct, improve efficiency in the administration of justice. Finally, other rules, like rules of privilege, are intended to affect out-of-court behavior. Evidence should be Material and Relevant.
Some evidence, even if material, relevant, and unprejudicial, may still be inadmissible if it was obtained in an illegal manner.
Types of Evidence
- Identification Evidence
- Attorney-Client Privilege
- Journalist-Source Privilege
- Physician-Patient Privilege
- Priest-Penitent Privilege
- Privilege Against Self-Incrimination
- Marital Confidences and Spousal Testimonial Privileges
- Similar Facts Evidence
- Acts that go to honesty
- Criminal Records
- Prior Bad Acts
- Testimonial Evidence
There are various types of evidence that a defense attorney will encounter during a case:
- Direct evidence is evidence which, if true, proves a relevant fact conclusively. For example, eyewitness testimony is a type of direct evidence. Direct evidence is not necessarily more reliable than any other kind of evidence. See, Eyewitness Misidentification. Direct evidence establishes a material fact without the need for any inferences to be drawn by the trier of fact.
- Circumstantial evidence is evidence which indirectly, through inference, aids the trier of fact in inferring the existence of a fact in issue. For example, fingerprints or DNA found at the scene would be circumstantial evidence. Circumstantial evidence can be more reliable than direct evidence.
- Judicial notice is evidence that the court declares is proven through authority or common knowledge.
- Real evidence is some actual physical item involved in the case. For example, the murder weapon is real evidence.
- Demonstrative evidence is a depiction, prepared for trial, that represents an item involved in the case. Following are some examples of demonstrative evidence: photo of the murder weapon, surveillance camera footage, computer simulations, diagrams, maps, x-rays, videotape, illustrations or any other item specifically created for trial.
A criminal defense attorney may object to real or demonstrative evidence on the following grounds:
- No identifying witness
- Gaps in chain of custody
- Opportunity for tampering or contamination occured
- Item is not a true or accurate depiction of what it purports to be.