Different jurisdictions have different types of speed limits. Some have what's known as absolute speed limits while others have presumed speed limits.

An absolute speed limit means that if you go even one mile per hour faster than the limit you are breaking the law. There is no wiggle room to argue one way or another.

For these types of tickets there are a few defenses. One of the most common ones is fighting the officer's method of determining your speed. Devices like radar and laser must be tested every few months. Sometimes pacing in some areas isn't allowed. If you attack the method by which your speed was read, you can get out of ticket. Other methods might include legal emergencies to speed, the speed limit signs being covered up or gone, or your car being mistaken for another.

Presumed speed limits means that you may be able to go faster than the posted speed if safe but at the same you could also be pulled over for speeding or an unsafe speed for prevailing conditions ticket if conditions are bad. This means that during an ice storm for example, going 55 miles per hour in a 65 zone might be considered dangerous.

To defend against these types of speeding tickets the idea is to prove that you were driving safe whether you were going over the presumed speed limit a little or driving faster than the officer thought you would have in less than ideal conditions.

This might involve diagramming the road, showing your viewpoint when you were pulled over, talking about what cars or lack of cars on the roads, or arguing your fairly good driving record free from accidents. It very well might be that you are used to driving on snow and ice while others in the area aren't, so your fast speed which seems normal to you seems dangerous to the officer or other drivers who aren't used to it.

It's always a good idea to check your local jurisdictions laws and interpretation of those laws. This is where you can find out what type of defense is needed and what the prosecution will have to prove to make you be found guilty of the violation.