Speeding tickets are, by far, the most common moving violation. If you want to fight your ticket, here are some things you should know about.

Speeding is one of the most common moving violations. If you want to fight a speeding ticket, it's important to know:

what type of speed limit you're accused of violating: “absolute,” “presumed,” or a “basic” speed law, and

how the officer measured your speed (pacing, aircraft, radar, LIDAR, or VASCAR).

This article covers the first piece—the different types of speed limits.

Three Types of Speed Limits

There are three types of speed limits that states use. We call these “absolute” (or “maximum”), “presumed” (or “prima facie”), and “basic” speed limits. Most states use two of the three types, while others use all three or only one type.

Because the available defenses are different for each type of speed-limit violation, it is key to understand which you are charged with violating.

Absolute Speed Limits

Most states have some absolute speed limits. There is no trick to how these limits work: If the sign says the maximum speed limit is 40 miles per hour and you drive 41 miles per hour or more, you've violated the law.

Presumed Limits

“Presumed” speed-limit violations are a little more complicated but give you far more flexibility in building your defense. In states that use this system for all or some of their roads—California and Texas, for example—it’s legal to drive over the posted limit as long as you are driving a safe speed. For example, if you are driving 50 miles per hour in a 40-mile-per-hour presumed zone, you're presumed to be speeding. But if it's 6 a.m. on a clear, dry morning with no other cars on a wide, straight road, and you can convince the judge that you were driving safely given those conditions, you should be acquitted. That’s because you present facts that “rebut the presumption” that by going over the limit you were driving at an unsafe speed. (There's more on this below.)

Basic Speeding Laws

The concept of the basic speed law is even trickier. Basic speed laws require drivers to always drive at a safe speed. So, you can be charged with speeding by violating a basic speed law, even if you were driving below the posted speed limit. The ticketing officer must simply decide that you were going faster than was reasonably safe, taking into account the driving conditions at the time. For example, if you're driving 40 miles per hour in a 45-mile-per-hour zone, but the road is icy and there's heavy fog, a cop could sensibly conclude that by driving too fast for road conditions you are in violation of the basic speed law. This type of ticket is mostly handed out after an accident.

Again, although there are three types of speed limits, each state has its own system. So, your state might not use all of the three types.

Find Out the Type of Speed Limit You Are Accused of Violating

The first place to look to determine what type of speed limit you were cited for violating is the ticket itself. In many cases, the ticket will say the code section of the law you allegedly violated. Or, the ticket might say something like "maximum speed limit."

If the ticket has the code number or no information indicating the type of violation, you'll want to look up your state’s law. Unfortunately, because of varying terminology, it's sometimes hard to tell from simply reading your state speeding law what types of limits the state uses. Here are a few things to keep in mind:

If your state’s laws refer to a “maximum” speed limit or says something like "unlawful to exceed" or "no person shall drive in excess," it is most likely an absolute limit.

If the law says it’s merely “prima facie unlawful” to exceed the posted speed limit, without reference to maximum limits and it doesn’t flatly forbid driving at a speed over the limit, the speed limit is likely presumed.

Basic speed laws normally say something like "it is unlawful driver faster than is reasonable and prudent" considering the current traffic and road conditions or specifically name the various road and weather conditions that require drivers to slow their speed.

Once you know the type of limit you supposedly exceeded, you can start looking to different types of defenses that might apply.

Absolute Speed Limit Defenses

The most common defenses to absolute speed limit tickets involve attacking the accuracy of the officer's speed measurement. For example, you might be able to successfully argue:

the officer's radar or LIDAR reading isn't reliable because the device wasn't properly calibrated

the officer mistook your car for another car, or

the officer paced your car incorrectly (attempted to drive the same speed) and therefore ended up with an inaccurate speed estimate.

Because these types of defenses are geared toward casting doubt on the officer's speed measurement or estimate, they can be used to defendant against all three types of violations.

“Presumed” Speed Limits: Defenses

With “presumed” speed limits, the question is whether the driver was driving an unsafe speed given the road and weather conditions at the time and place the violation allegedly occurred. If you’re accused of violating a presumed limit, you generally have two possible defenses:

arguing you weren’t exceeding the posted speed limit (just as you would if you were charged with violating an absolute speed law), or

claim that, even if you were exceeding the posted limit, you were driving safely given the specific road, weather, and traffic conditions at the time.

Occasionally an officer will incorrectly measure your speed. But even when that happens, it can be hard to convince a judge to accept your version of the story. So, for presumed violations, it's often more effective to rely primarily on the argument that you may have been driving slightly over the posted speed limit, but it was safe to do so considering all the highway conditions at the time. For example, if you know you were driving 33 to 35 miles per hour in a 25-mile-per-hour zone, you should concentrate your defense on showing that your speed was safe because of factors like sunny skies, no traffic, and perfect visibility.

The “Basic” Speed Law

Because basic speed laws focus on driving a safe speed, as with presumed limits, the question comes down to whether the driver was going a speed that was reasonably safe in relation to the conditions that existed at the time.

For example, driving exactly at the 65‑mile-per-hour posted limit on the freeway would be really dumb amidst slower and heavy traffic, in a dense fog, or in a driving rainstorm or blizzard. In commonsense terms, such unsafe driving is unlawful, regardless of the posted speed limit. Police most often rely on the basic speed law after an accident. The reasoning is that you were driving too fast, no matter how slow you were driving, because you were in an accident.

The difference between fighting a basic speed law ticket and a speeding ticket for going over a presumed limit is that the government has the burden of proving you were driving unsafely. With presumed limits, it's flipped: Once the government shows you were driving faster than the presumed limit, it's up to you to prove your speed was nevertheless safe. In other words, the officer must testify that given the road, weather, or traffic conditions, your speed was unsafe.

Tailor Your Defense To What The Officer Says

Before you testify, you’ll have a chance to listen to what the officer says and to cross-examine him. If you work quickly, you’ll have the opportunity to tailor your testimony to his answers. For example, if the officer's testimony focuses on road or weather conditions that might have been unfavorable, you could testify as to the aspects (like good visibility) that go the other way.

Added Caution Is Necessary In Cases Involving Accidents

If you were involved in an accident, it's best to talk to an attorney about your case. In addition to the penalties for a speeding violation, you might also be facing a lawsuit. Getting an attorney's assistance in this situation is a good idea.