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Are Speed Traps Legal?

One of motorists' most common interactions with police is a traffic stop for exceeding the posted speed limit. Often, the police car seemingly comes out of nowhere, perhaps hidden behind a tree-lined curve in the road. This stealthy method of speed enforcement is often called a “speed trap."

While this type of traffic enforcement can be frustrating for motorists, it is generally legal in all states.

Law enforcement agencies and police departments use speed traps for several reasons. The most common goals are to improve highway safety, reduce auto accidents, and generate revenue from speeding tickets.

Basic Speed Trap Laws

The legality of speed traps depends on state and local laws and how different jurisdictions define the term. Each state sets its own laws for how they speed traps and specifics on how they can be used.

For example, the California Vehicle Code prohibits using marked road traps and unjustified speed limit traps. A marked road trap is a section of highway designated for measuring the speed of a vehicle by calculating the time it takes to travel a known distance.

An unjustified speed limit trap refers to a section of highway with a lower speed limit not justified by a traffic survey conducted within the past five years. Traffic surveys analyze transportation conditions and patterns to inform laws, planning, and management.

Even considering the detailed legal language above, most speeding enforcement methods are legal in a majority of states, even California. This means an officer with a radar gun parked behind a tree-lined curve or otherwise hidden from view is not violating the law in either California or virtually anywhere else.

Since speeding laws differ by state or municipality, check your local laws for more specific guidance. However, police are generally not required to announce their presence when enforcing speed limits.

Speed Cameras, Hidden Officers, and Entrapment

Motorists often use the term speed trap to describe a range of stealthy police tactics used to enforce speed limits and other traffic violations. A few of these common practices and terms include:

  • Traffic cameras, speed cameras, and automated traffic enforcement
  • Officers on private property
  • Police entrapment

While the systems above are sometimes discussed alongside speed traps, they actually have very different definitions and legal implications.

Traffic Enforcement Cameras

Using discrete traffic cameras to enforce speed limits is a separate legal issue from speed traps. These automated enforcement systems use mounted traffic cameras to identify speeders. Law enforcement then uses this information to issue the driver a citation, usually by mail.

This type of automated traffic enforcement is not permissible everywhere and depends on state law. Some states that formerly used this practice have chosen to discontinue it. For example, Arizona used hidden radar guns to check motorists' speed and snap photos of speeding drivers' license plates. Speeders would receive citations in the mail, but the governor halted this camera program in 2010 in response to civil liberties complaints.

Police Entrapment

Law enforcement officers may not use methods of entrapment to make an arrest. In this context, entrapment refers to law enforcement encouraging motorists to break the law so they can issue a ticket. Although police officers hiding to catch speeders is often called entrapment, that is not the accurate legal term. If you are speeding, the officer hiding from view is irrelevant if they did not influence you to exceed the speed limit.

Hidden Officers and Trespassing

An officer hiding on private property must comply if a property owner asks them to leave. Even if a dispute arises between a property owner and an officer who ignored requests to leave, any tickets or arrests made by the officer remain valid. The citation or arrest cannot be challenged on that fact alone. Even if the court finds the officer was trespassing, you are still on the hook for that traffic ticket.

Suppose an officer parks on a private road or driveway clearly marked with a "no trespassing" sign. The same rule would apply: The property owner may file a complaint against the officer for disregarding the sign, but any legal stops or arrests from that location remain valid.

Homeowners often welcome officers to their driveway to tame traffic near their homes. Law enforcement presence in or near your neighborhood can encourage responsible driving and improve traffic safety.

Avoiding Speed Traps

You can encounter speed traps anywhere, but they are more commonly found and enforced in particular areas. Some of these locations include:

  • School zones
  • Construction areas
  • Residential areas
  • Intersections or roads with high accident rates
  • Tourist areas
  • Transition areas where the speed limit changes from a higher limit to a lower limit

The best way to avoid speed traps is to drive responsibly and be aware of your surroundings. If approaching any of the areas above, check the posted limit and prepare to reduce your speed.

Caught by a Speed Trap? Consider Your Legal Options

Getting pulled over for speeding is never an enjoyable experience. If law enforcement issues you a speeding ticket, there are situations in which they may have overstepped their boundaries. If you believe you were subject to an illegal speed trap, talk to a traffic ticket attorney near you.

A local attorney can review the circumstances of your citation and your local motor vehicle code to determine if the method used to determine your speed was legal. Getting a speeding ticket dismissed in traffic court can save you an expensive fine, increased auto insurance costs, and points on your driver's license.

For more information on speed traps and broader traffic laws, see FindLaw's extensive Traffic Laws section.

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