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Expert Witnesses in Maryland DUI Cases

There are going to be several kinds of expert witnesses that the prosecution needs in a DUI case. Simplest is just the arresting officer. There are some types of field sobriety tests, specifically the Horizontal Gaze Nystagmus Test, that require that the officer be certified as an expert in the administration of that test before the testimony can be admitted as to the performance on the test.

Different states’ attorney’s offices have different policies in regards to that test. Many states’ attorney’s offices just do not seek to admit that test because they do not want to go through the hassle of fully qualifying the officer as an expert. Other states’ attorney’s offices will submit a form to the defendant and the defense attorneys saying that they intend to qualify the officer as an expert and then they will seek to do that in court. That will allow them to testify in the court the results of the Horizontal Gaze Nystagmus test.

The other types of experts that the state will call in a DUI case frequently will be medical experts. If an individual submits to a hospital blood draw, rather than a state evidentiary blood draw, the state will need to bring in an expert witness to explain the results of the blood draw to the court. It cannot take a presumption based on a hospital blood draw that the individual’s level of impairment was sufficient to qualify him or her for a DUI per se.

Defense-Side Expert Witnesses

The defense can call expert witnesses for several different purposes. One may be an accident deconstructionist to bring forth the facts of the accident that can exonerate the defendant. The defense can call a medical expert perhaps to explain the evidence of impairment as not being caused by alcohol or drugs but rather by an underlying medical condition. The defense will call experts to elucidate certain facts that need a more technical explanation than a lay witness can provide.

In a lot of cases, when there is going to be a battle of experts where the state will call an expert and the defense will call an expert, are really going to be decided based on the believability of the individual expert witnesses. The quality of the defense attorney’s expert witnesses is going to be absolutely important for the impact on the outcome of the case.

Weight of Expert Witness Testimony

The expert is allowed to testify on direct examination by the party that calls the expert and will be open to cross examination by the opposing parties. If it is a state witness, for example, the expert will testify and answer the state attorney’s questions. Then the defense attorney will have a chance to cross examine the witness and bring out any evidence or make the testimony less credible. The weight given to expert testimony that is something that the individual finder of facts will decide. It will be up to the judge or the jury to assign weight and significance to expert testimony.