Are Speed Traps Legal?
One of the most common interactions motorists have with the police is a traffic stop (and resulting citation) for exceeding the speed limit. Often, the police car seemingly comes out of nowhere, perhaps hidden behind a tree-lined curve in the road. But are speed traps—the common term for stealthy speed enforcement methods—even legal?
Basic Speed Trap Laws
As with most laws enforced at the state or local level, it depends. It also depends on how different jurisdictions define the term.
The California Vehicle Code (CVC 40802), for instance, prohibits the use of “marked road traps” and “unjustified speed limit traps.” A “marked road trap” is defined as a section of highway “marked, designated, or otherwise determined” for measuring the speed of a vehicle by calculating the time it takes to travel that distance. An “unjustified speed limit trap” is a specific section of highway with a lower speed limit that is not justified by a traffic survey conducted within the past five years.
Motorists use the term "speed trap" to describe a whole range of stealthy police tactics used to enforce speed limits and other traffic regulations. Most of these methods are perfectly legal in most states, even California. So an officer with a radar gun parked behind a tree-lined curve in the road, or otherwise hidden from view, is not violating the law in California or virtually anywhere else.
Since speed enforcement laws differ from state or local jurisdiction to the next, check your local laws for more specific guidance. Generally, though, police are not required to conspicuously announce their presence when enforcing speed limits.
Hidden Cameras and Hidden Officers
The use of hidden cameras to enforce speed limits is another matter. Arizona, for example, used hidden radar guns to check motorists’ speed and then snap photos of speeding vehicles’ license plates. Speeders would receive citations in the mail. But the governor halted the program in 2010 in response to civil liberties complaints. See “Speeding and Red Light Camera Tickets” for more details.
In any case, officers may not use methods of entrapment—the act of encouraging motorists to break the law—in order to induce an arrest. Although the act of hiding by police officers often is called entrapment, that is not the case. If you are speeding, the fact that the officer was hidden from view is irrelevant if you were not influenced by the officer to exceed the speed limit.
Additionally, an officer hiding out on private property must comply if a property owner asks them to leave. But 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 and cannot be challenged on that fact alone. So even if the officer is found to be trespassing, you are still on the hook for that traffic ticket. Homeowners often welcome officers to their driveway in the interest of taming traffic near their homes, or at least do not mind their presence.
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 made from that location remain valid.
For more information related to speed traps and traffic laws in general, see FindLaw’s extensive Traffic Laws section.