Last November I was hired to consult on a case where three motorcycles were accused of traveling 129 mph in a 55 mph zone. In the Commonwealth of Virginia 74 mph above the speed limit is a serious offense, trials take place in criminal court. There were only two defendants because one of the motorcycles did not stop for police. The police eventually found out who he was but chose not to go after him, two out of three ain't bad. The same attorney represented both defendants and both were tried at the same time with a jury. The defendants were looking at a heavy fine, jail time, and driver's license suspension. The defendants license's were automatically suspended when arrested, about 6 months and counting.
The police officer's notes and both defendant's agreed on the general circumstances. The three motorcycles were traveling on a six lane highway, three lanes each direction. There was a a 45 foot grass medium between opposite direction traffic. Shortly after the motorcycles came around a curve they spotted the patrol vehicle traveling in the opposite direction. One of the motorcycles bolted just after spotting the police. The patrol car just happened to be approaching a medium crossover shortly after the radar registered a 129 mph reading and made a u-turn to go after the motorcycles, one got away.
The attorney did a good job supplying me with documents, both sides account of the event and the exact location. Aerial maps were good enough to get accurate estimates of distances, positions, angles, and timeline. There was enough data to run a radar simulator model to reconstruct events and predict radar performance. The model showed it was highly unlikely the radar had time to get a reading, cosine effect limitations at close range being the main factor. The numbers showed at most the radar had 0.3 seconds to get one reading - not enough to be considered reliable. Many localities require a minimum track time of three to five seconds to be considered reliable. Based on the data and events I had no doubt in my mind the motorcycles were not traveling anywhere near 129 mph.
While preparing for trial I asked for any patrol car dash camera video to tighten up the data runs. Video was available but the prosecution was having trouble locating it. Two days before the trial the prosecutor emailed a copy of the video to the defense attorney, but he never received it. The morning of the trial with less than an hour to start the prosecutor admitted she inadvertently emailed the video to herself. We were finally able to view the video just before the trial started. The first thing I noticed was the video did not have any information overlaid on the display, radar patrol and traffic speed readings, date, time tags, patrol vehicle number and such.
What actually happened was right around the point the computer model predicted the radar could get one speed reading, one of the three motorcycles bolted, the one that got away. The acceleration was impressive and explains the 129 mph momentary false speed reading, it was speed batching or bumping. All moving mode radars are susceptible to speed batching/bumping, caused by a sudden change in speed. If the speed change is fast enough speed batching causes measured speed to be two or three times greater than actual for a brief moment. In this case the motorcycles were most likely traveling at 65 mph when one of the motorcycles punched it hard.
The trial starts and even before jury selection the judge makes it clear he is in a hurry. He restates this several times throughout the trial, it was a Friday and he had another trial that day. The prosecutor sandbagging, missing data on the video, and the hurry up judge were omens of things to come.
As a matter of standard procedure I suggested to the defense attorney to question the officer about testing the radar with tuning forks. My experience has shown this is misunderstood among many officers. In court the officer showed how she held the tuning fork when testing, it was wrong. Additionally the results the officer got when testing moving mode could not have resulted from the resonances of the forks being used. This suggest the radar was not tested with tuning forks.
When it came time for my testimony the prosecutor questioned my expertise, standard procedure and fully expected. The prosecutor finally admitted I was a radar expert, but not a police radar expert. The judge disallowed my testimony. When I asked the judge if I could testify as a knowledgeable witness he calmly said I should sit down. This situation was somewhat ironic as every law library in Virginia has a copy of "Defense of Serious Traffic Offenses in Virginia" published by Virginia CLE (Continuing Legal Education) Publications in which I wrote Chapter 6 - Technical Defenses in Speed-Related Cases.
Things went down hill after that. The jury was able to watch the video in court, but not all of them had a good view of the laptop screen and they only saw it once. During deliberation the jury asked to view the video again, the judge said they had to go on what they saw in court. The jury found the defendants guilty, but imposed a much smaller fine than expected, no jail time, and no loss or suspension of driver license. It was still a high price for traveling 10 mph over the speed limit. The net result is the motorcyclists, not the one that ran from police, came out far better than they otherwise would have without a technical expert on their side.