Competency to Testify
As a general rule most witnesses are presumed to be competent and able to give reliable testimony. However, competency may be tested for each individual witness. In the U.S. Federal Courts, competency is determined on a case by case basis. Following are some of the situations a criminal defense attorney may encounter regarding testimonial competency.
Following are general requirements for competency:
- Oath or Affirmation - In many courts every witness shall be required to declare that the witness will testify truthfully, by oath or affirmation administered in a form calculated to awaken the witness' conscience and impress the witness' mind with the duty to do so. If the individual does not understand the oath or affirmation, then they may be incompetent to testify.[1]
- Knowledge - A witness is only competent to testify if they have personal knowledge of the facts that they will testify. [2]
- Language
Mentally Disabled
Children
Spouses
Judges
Because of the inherent conflict of interest, a judge should not be allowed to testify as to facts in a trial over which she is presiding. [3]
Jurors
A juror should not be allowed to testify as to the facts in a trial over which she is a trier of fact. However, in certain circumstances a juror may be called to testify as to whether extraneous prejudicial information was improperly brought to the jury's attention, whether any outside influence was improperly brought to bear upon any juror, or whether there was a mistake in entering the verdict onto the verdict form. [4]
