Experts have special education, training, or experience that allows them to testify to their opinions on matters beyond everyday understanding. They aren’t bound by the personal knowledge rule, meaning that they need not have directly observed the facts underlying the case. They can give opinions based on information provided by other witnesses or contained in written reports. Also, unlike other witnesses, experts can and do receive payment for testifying.
Example: Hap Hazard is on trial for robbery; the defense is an alibi. Hap wants the jury to understand the factors that he claims caused the eyewitnesses to mistakenly identify him as the robber. Hap can probably offer expert testimony to support this claim. Most courts have ruled that factors affecting witnesses’ ability to observe and recollect are sufficiently beyond everyday understanding to allow experts to testify. In this case, Hap might hire a forensic cognitive psychologist to testify about factors that could have led to misidentification.
Even if they don’t testify, expert witnesses can be helpful in persuading the prosecution that a reduction or dismissal of charges is necessary. Consider an expert in blood-alcohol analysis. If that expert determines that the government’s report indicating that the defendant was over the legal limit while driving is fundamentally flawed, the defense might be able to persuade the prosecution to dismiss charges.
Expert witnesses can be very expensive. They often bill on an hourly basis at a high rate, not only for their testimony, but also for the time they spend preparing. Experts are sometimes crucial, and the stakes often make it worth it for the defendant to dig deep to find the requisite funds.
It’s not unusual for an expert to charge defendants a few thousand dollars for what amounts to a day of testimony. Fees are less of a problem for prosecutors, because fingerprint experts, ballistics experts, and laboratory technicians often are already on the government payroll. In serious or high-profile cases, prosecutors will often hire outside experts since the government, not the prosecutors themselves, ends up footing the bill.
Court-appointed lawyers don’t have the funding to hire an expert on every case. However, a court-appointed lawyer can petition a judge to appoint an expert. If a judge considers an expert’s opinion legally necessary or helpful to a fair resolution of the case, the judge can appoint an expert at government expense. For example, an expert who might charge private clients $3,000 might have to accept $750 per day for a court-appointed case (assuming the expert agrees to participate at those rates).
Example: Nell Shrap is on trial for making a telephoned bomb threat. The prosecutor’s primary evidence is an audiotape of the threat. A government voice identification expert is prepared to testify that the voice on the tape is Nell’s. Nell is indigent. Her attorney can file a pretrial motion asking the court to appoint a voice identification expert at government expense. If the judge grants the motion, the defense expert can evaluate the recording, consult with Nell’s attorney, check the procedures of the prosecutor’s expert, and testify on Nell’s behalf at trial.
If you are facing criminal charges, consult an experienced criminal defense lawyer. Only such an attorney can properly evaluate your case and explore the potential usefulness of an expert witness. That lawyer can also advise you of the potential cost, and whether government funding is possible.