The Impossibility Defense in Speeding Cases
I talk to clients every day about Reckless Speeding cases in Virginia. One of the most common complaints they have is that the cop must have it wrong because they couldn't go that fast in their car, or they couldn't go that fast on that road. In Fairfax County Reckless cases, clients often make these claims when they are accused of speeds in the mid 80's.
There are a few big problems with the Impossibility Defense which make it almost impossible to win your case. First, if you are going to testify, you will do so after the officer. So, the officer has already testified that they measured you at a specific speed.
The judge will be listening to your testimony to hear how fast you were going. If you tell him your speed, then he will want to know how you are sure of it, and whether you had your speedometer tested.
If all you have to offer is the Impossibility Defense, then it is like saying "I don't know how fast I was going, but here is why the officer is wrong.". Even worse, it can have the effect of saying "Even if I was going as fast as possible, I couldn't go that fast". This doesn't help much, because it sounds like you were going as fast as you could.
Finally, you are left with this logical dilemma: If the judge believes that it IS possible to drive that fast, then you have a guaranteed conviction because he has already decided that you are wrong!