The answer is subjective, depending on whether the device was working properly, and whether it was used properly. Subpoena the manual to determine the device's proper use and capability. Subpoena the maintenance log to determine whether the machine has been tested and has been working properly. You could subpoena the officer's training records to determine whether the officer was properly trained. However, good luck finding a judge who will not believe a cop.

Be prepared that the police may fight the subpoena, or they may require you to pay for the copies.

It appears the OfficerTrooper obtained your speed using a LIDAR or Laser device. (If you look on your citation, the "Arrest Type" will be either "Q" or "R." Even though LIDAR is the most accurate device used for determining speed in Maryland, there is still a margin of error of +/- 1 MPH. That MoE is significant in your case, especially if you are a Maryland-Licensed driver, because reducing the speed to 84 MPH reduces the violation from 5 points to 2 points.

There are several other items to be subpoenaed. The defense of speeding tickets is very technical in nature. The way the law is written, regardless of reason, if you are traveling above the posted limit (in this case, 55 MPH), then you are guilty of speeding. You MUST keep the speed out of evidence to win. You probably want to speak with an attorney who is experienced in fighting speeding tickets. My practice has concentrated in traffic defense for the past 15 years.