Expert Witnesses are available to review the validity of the breath test or blood test. In addition, an Expert Medical Witness may help if you have medical conditions that would affect your ability to perform the standard field sobriety tests. If your case involves a DRE, or Drug Recognition Expert, an expert could greatly assist in your defense. Almost all cases benefit from the assistance of these experts. I personally recommend that you retain an expert witness to assist with medical, testing, and DRE issues.