We've all been there. That moment when you're running behind and you know that you're pushing it just a little bit and then you get that nasty feeling in the pit of your gut as you realize the police car you just passed is starting to move. You keep glancing in the rearview mirror and sure enough, the lights come on and he starts catching up to you. You hope that he's going to pull ahead of you at any moment but you know he's about to pace behind you and once again you're going to have to decide whether to pay or to fight a speeding ticket.
Many people have successfully fought speeding tickets based on "personal emergency", however, the guidelines for this sort of battle are very stringent. Most police officers won't give you the ticket if you are in the middle of an emergency, like on your way to the hospital. In fact, if you can communicate that fact to them, you may find yourself with a police escort to the hospital.
Outside of a significant emergency such as rushing off to the hospital or to the side of a loved one's death bed, "personal emergency" doesn't excuse the behavior and it is very difficult to fight a speeding ticket in this manner.
More effectively, the two most common claims against a speeding ticket include ill posted signs and inconclusive speedometers. Usually, a police officer will give most cars a five mile per hour speed leeway, as speedometers are not considered to be calibrated at pinpoint accuracy. It is not uncommon for speedometers to be off by about 5 miles per hour. This won't get you out of a speeding ticket if you were pulled over for doing 75 in a 35 zone, but if you're talking a few miles per hour, you have a reasonable claim to fight a speeding ticket.
Ill posted signs are actually all over the place. In most states, the residential speed limit for any residential area is 35 miles per hour. Once the road returns to more open highway, it is assumed unless otherwise posted that the speed limit returns to either 55 miles per hour or 65 miles per hour, depending on the road and state law. If the road is devoid of the sign signifying the end of the 35 mile per hour zone, then it is unreasonable to assume that drivers can telepathically understand where the reduced speed zone ends. Under these circumstances a driver can usually successfully fight a speeding ticket.
Of course, avoiding the speeding ticket is the most sensible way to fight a speeding ticket. Yet each of us will find ourselves running late for an important meeting or appointment and we will gun the accelerator just enough to push the envelope in hopes of shaving just a few minutes off our travel time.