For some criminal prosecutions, the government will go to great lengths to influence a jury to convict a defendant. Prosecutors will often retain and call expert witnesses to testify in support of a guilty verdict. Expert testimony is not always permitted, though when experts are allowed to testify on the state’s behalf, their testimony can significantly harm a defendant’s defense. The Texas Court of Criminal Appeals recently released a decision that sheds light on their qualifications and the admissibility of their testimony.
According to the facts discussed in the appellate opinion, the defendant was charged with a Texas domestic violence offense. At trial, the prosecution sought to prove the elements of an aggravated offense, and the defendant was sentenced to five years in prison. The defendant appealed his conviction, arguing that the state inappropriately used an expert witness who unfairly influenced the jury to convict him of the aggravated offense.
On appeal, the Court found that Rule of Evidence 702, which governs the admissibility of expert testimony, plays a pivotal role in determining whether an expert witness’s testimony will be considered in court. Under this rule, three conditions must be met before expert testimony becomes admissible: qualification, reliability, and relevance.