Presiding over a case that involves DNA evidence is a challenge that requires thorough knowledge of constitutional rights, science, police procedure, and the management of discovery and expert witness issues. This module will address the pretrial and trial aspects of these issues.


Statutes of Limitation

Case law is continually responding to the developments and applications of forensic DNA. For example, courts have held that DNA evidence is legally sufficient to convict even without identification of the accused by a live witness.

Expert Assistance

The evaluation of DNA test results may require expert assistance. An expert can educate and advise the defense team, and possibly serve as a witness. If the defendant is indigent, an expert can be obtained by motion to the court requesting funding for such assistance.

Input From an Expert

An expert for the defense can help with complex and technical matters, such as:

  • Interpreting the prosecution's laboratory report and underlying data
  • Determining whether there were problems with the laboratory analysis and/or evidence handling
  • Evaluating the need for independent testing and observing additional testing procedures.
  • Offering testimony at trial
  • Preparing counsel for the presentation of DNA evidence at trial
  • Determining whether to challenge the admissibility of newer DNA technologies

Financial Assistance

A defendant has a constitutional right to expert assistance financed by the court or prosecuting county. This right is not absolute; there will be an assessment of the probable value of the assistance sought and the risk of error if such assistance is not obtained. Thus, the defense motion needs to detail the client's indigent status and the specific reason(s) the expert assistance is required.

Defense Testing

The defense may request testing of items not yet tested by the prosecution or the retesting of items already examined by the government. Such requests must be evaluated on a case-by-case basis with reference to the defense proffer of why each test might provide exculpatory evidence. The court should also be aware of backlogs in local law enforcement DNA labs and the need for appropriate prioritization of testing requests.