Understanding How Police Use Radar Guns in Texas

In Texas state, a municipality is not allowed to operate an automated traffic control system that involves using a radar device to record the speed of a motor vehicle. This law is the only law in Texas statutes that relates to law enforcement officers’ use of radar devices in speed traps.

This state law does not prohibit police officers of city police departments from using radar devices to monitor drivers' speeds. Police officers may use radar devices to issue speeding tickets to drivers traveling above the speed limit, but cannot set up an automated system to do so.

A radar detector is an electronic device that a driver puts in a car to determine if the car’s speed is being monitored by law enforcement officers with a radar gun. If a driver learns that a police officer or sheriff is using a radar gun, they can slow down before approaching the officer. A radar detector can detect a police officer from between 2 and 4 miles away.

Technologies like cruise control and lane assist can affect a radar detector’s signal. ‌The answer to the question, “Is the use of radar detectors legal in Texas?” is yes, except for commercial vehicles that weigh over 10,000 lbs., such as a semi-truck.‌

The regulation regarding commercial vehicles is a federal law found at 49 Code of Federal Regulations (C.F.R.) Section 392.71(a). A Texas police officer or a sheriff’s deputy can ticket the driver of a commercial vehicle for violating this federal law.

Police radar consists of radar guns that transmit radio waves that bounce off targets and reflect back to the radar transmitter. Police officers employ radar to determine the speeds of nearby vehicles. Police radar guns can target multiple vehicles at a time.

Police radar guns are usually accurate within a 1 mph of a vehicle’s speed. It senses the speed of a vehicle in less than a second. A police officer can use a device called a radar detector detector (RDD) to determine which cars on the road have radar detectors.

Doppler radar systems allow law enforcement officers to determine the movement of a target and its position. When a device transmits pulses of radio waves, the system tracks the phase (shape, position and form) of the pulses.

The system calculates the target’s movement by measuring the shift, or change in phase, between a transmitted pulse and a received echo. A positive shift indicates there is motion toward the radar gun. A negative shift indicates motion away from the radar gun.

Lidar stands for “light detection and ranging.” It is a remote sensing method that uses light waves to detect the speed of a moving vehicle. The technology consists of a police lidar gun, which is essentially a laser.

The lidar gun emits a beam of infrared light at a moving vehicle to determine the vehicle’s speed. A lidar gun is more accurate than a radar signal gun because the lidar gun calculates speed by observing how much time it takes to sense the reflected pulses of light over a certain amount of time.

Law enforcement officers are permitted to use radar guns and lidar guns to measure the speeds of vehicles.

A radar gun needs a direct line of sight to work well. Buildings, trees, hills and curves can get in the way of a signal. Traffic and other vehicles can also prevent a radar gun from sensing the speed of a target.

A lidar gun also needs a direct line of sight to work effectively. Lidar guns work the best if they are stationary, or mounted, in a fixed location. Rain, sleet, snow and hail can interfere with the accuracy of lidar measurements.

Signal jamming devices, including radar jammers, are illegal under federal law. The Federal Communications Commission provides no exemptions for use within a vehicle.

It is unlawful to advertise, sell, distribute, import or market jamming devices to consumers in the U.S. The use or sale of a jammer can subject the user or seller to incarceration, fines and seizure of the unlawful equipment.

There are many smartphone apps that can detect cop cars. The apps work by users of the app marking the location of speed cameras and police patrols. Popular apps include Waze Navigation & Live Traffic and Police Detector.

Speeding is a moving violation, as stated in Texas Administrative Code Title 37 Rule 15.89. In Texas, speeding is usually a misdemeanor. The severity of a speeding offense depends on the locations and conditions of the speeding. Typically, misdemeanors are punishable by up to one year in jail, as well as a fine.

The amount of the fine depends on the severity of the offense. Reckless driving is defined as driving a vehicle in wilful (intentional) or wanton (obvious) disregard for the safety of persons or property. Reckless driving is a misdemeanor punishable by up to one year incarceration and a fine up to $200.

A person’s driver's license may be suspended if they are convicted of four or more moving traffic violations within one year or seven or more moving traffic violations within two years.

When the Texas Department of Transportation suspends or revokes a person’s driver's license, they are notified by mail to the address on record for their license. The notification provide the reason for the suspension or revocation and, if available, an option for a hearing.

The person can request a hearing up to 20 days after the date of the notice. They should allow up to 120 days for the hearing to be scheduled. The Texas Department of Transportation will notify the person by mail of the date, time and location of the hearing.

If a person requests a hearing after 20 days of the date of the notice, the Texas Department of Transportation will deny the person's request. The Department will notify the person of the denial by mail. If the person has already been through the administrative hearing process and the decisions resulted in the suspension of their driver license, they may be eligible to appeal that decision.

Before the person has their driver's license renewed or reissued, they must pay all required reinstatement fees. They may be eligible to apply for an occupational license while their driver's license is suspended or revoked. An occupational license allows them restricted driving abilities, such as driving to their job or school.