There are countless precedents of VASCAR speeding tickets (cop observes car drive over line A, starts timer until car drives over line B, resulting in a speed) being overturned because of parallax shift.
"The only sources of error in VASCAR are the Officer's reaction time in pressing the start/stop timing button
and his judgment on precisely when a vehicle was passing a landmark. In the case if the bridge shadows, the second error possibility is almost zero, but for an Officer in a moving Police car, determining the precise second when you, a quarter-mile ahead, pass some landmark, could be off by a number of feet. If an Officer would use a baseline of 60 seconds or so, a one second error would only represent 1.5% error. But that's an awfully long baseline. Essentially, VASCAR determines your AVERAGE speed for the measured distance. (RADAR determines your instantaneous speed). In a mile long stretch of highway, most drivers would see the Police car and severely slow down. Since he is only determining the AVERAGE speed for that distance, that average would be substantially less than your beginning speed. Therefore, most Officers tended to use the shortest possible baselines for VASCAR, to get a speed average before you might see him and slow down. If he used a 10-second baseline (around a block and a half), a half-second error in clicking the beginning time and a half-second error in clicking the ending time could total a one second error, which represents a 10% error in speed determination (either up or down). (That type of poor Officer understanding of VASCAR is a main reason it got replaced by radar. Some Officers would try to use even shorter, five-second baselines to get a speeding value even faster before being seen. Such Officers really gave VASCAR a bad name because they would sometimes get VASCAR results that were 20% off. A vehicle actually traveling a legal 65mph would be arrested for going 78mph, because of the incorrect use of too short a baseline. A lot of people got improperly arrested because of that. Eventually, some important people got improperly arrested in that way, and RADAR came along anyway, so VASCAR almost disappeared from Police use.)"
http://mb-soft.com/public/radar.html