The green light on top of a police car serves an important purpose – it indicates when the officer is on patrol. This flashing green light lets the public know that the officer is actively monitoring traffic and responding to calls in the area.
Purpose of the Green Light
There are a few key reasons why police cars use a green light:
- Visibility – The green light makes the patrol car more visible to other drivers. This allows motorists to see the police vehicle from further away.
- Alertness – The flashing green light signals to drivers that a police officer is actively patrolling and enforcing traffic laws in the area. This encourages motorists to be more alert and follow the rules of the road.
- Deterrent – The presence of a marked police car with a flashing green light can deter speeding, illegal passing, and other violations. Drivers are less likely to break traffic laws when they know an officer is nearby.
- Safety – The high visibility of the green light promotes safety. Motorists, pedestrians, and bicyclists are all more likely to notice the police car and exercise caution.
So in summary, the green light is used to make the public aware that an on-duty officer is present, to promote adherence to traffic laws, and to increase overall safety on the roads.
When the Green Light is Used
Police departments have policies about when officers should activate the green “patrol” light on their vehicles. Here are some common situations when the green light is turned on:
- Routine patrol – Officers will use the green light when normally patrolling their beat or assignment area. The flashing light signals their active presence as a deterrent to crime and traffic violations.
- Traffic enforcement – Officers often turn the green light on when enforcing traffic laws, like during speed enforcement, DUI checkpoints, and seat belt compliance campaigns. The light makes their traffic enforcement activity apparent.
- Accident response – At the scene of an accident, the green light alerts oncoming traffic to the official police activity ahead.
- Pulling vehicles over – During traffic stops and other vehicle detentions, the green light is used to signal it is an on-duty police officer making the stop.
However, some departments prohibit use of the green light during certain situations where visibility of police activity could be a safety issue. This includes undercover or surveillance work where maintaining a low profile is important.
Distinguishing from Other Colors of Lights
The green police light serves a different purpose than the other colored lights often seen on top of squad cars:
- Red – Flashing red police lights indicate an emergency response or urgent situation. They are used when responding to critical calls for service.
- Blue – Solid or flashing blue lights are associated with general law enforcement activities. They may be used during regular patrols or traffic enforcement.
- White – White lights illuminate the officer’s immediate area and are often used along with the vehicle’s high beams when conducting field investigations at night.
- Amber – Amber/orange lights are secondary to the main red, blue and green lights. They provide additional visibility to the vehicle.
The green light specifically conveys “officer on patrol” status and serves a separate purpose from emergency or general operational lighting.
When Multiple Lights are Used
Police vehicles are equipped with multiple colored lighting systems. Here are some common combinations and situations when multiple lights are used:
- Green + Red/Blue – Officers may use the green light concurrently with flashing red or blue emergency lights when responding to calls for service. This conveys their active patrol status during the emergency response.
- Green + Blue – Leaving the green light activated while using the blue lights is common during regular enforcement stops like traffic citations. It indicates the stop is part of their on-duty patrol activities.
- Green + White – Officers often activate the green patrol light together with their white scene or takedown lights when investigating incidents or conducting field sobriety tests.
- Green + Red/Blue/White – During major incidents, officers may use all lights together to maximize their visibility and presence.
The ability to use multiple lighting systems provides officers with flexibility to signal different modes of operation depending on the specific circumstances.
Regulations for Use
Most police departments have policies regulating usage of the green “patrol” light:
- Officers may only use the light while actively on duty and engaged in their official duties.
- The light should be activated whenever conducting routine patrols, traffic enforcement, or other proactive field activities.
- Use is prohibited outside the jurisdiction or while off-duty, except in circumstances approved by a supervisor.
- Officers responding to emergencies must follow applicable state laws regarding required lighting for emergency vehicles.
- Specialized units in unmarked cars should avoid use of the light during covert or surveillance activities.
- When parked, the green light may remain activated to indicate an officer’s on-duty status.
Improper or unauthorized use of the green patrol light may result in counseling or disciplinary action. Officers must follow their agency’s procedures regarding appropriate activation of the light.
History of the Green Light
The use of a green police light has its origins in the 20th century:
- 1920s – Early police cars experimented with a variety of colored lights, including green. But standards had not yet been established.
- 1930s – By this decade, red lights had become common for police emergency vehicles. Blue was also in use by some departments.
- 1940s – Los Angeles Police Department pioneered use of the green “patrol” light in the late 1940s to distinguish routine patrol units from other special service vehicles.
- 1950s – Use of the dedicated green patrol light spread nationwide throughout the 1950s as more agencies adopted LAPD’s standards.
- 1960s – Reflectorized lighting technology advanced during this decade, improving the visibility of the green light.
- Modern day – The green patrol light remains in widespread use on police vehicles across the country as a distinctive marker of active-duty status.
While LED lights have replaced earlier incandescent bulb technology, the purpose and function of the green light remains essentially unchanged since LAPD first introduced the concept back in the late 1940s.
Exceptions and Variations
Most American police agencies use a green light to denote a patrol vehicle, but there are some exceptions and international variations:
- In some jurisdictions, a steady burning green light indicates a volunteer firefighter’s personal vehicle responding to an emergency.
- The NYPD uses a steady green light to identify the personal vehicles of officers assigned to headquarters duty or administrative roles.
- In the UK and many former British Commonwealth countries, the standard police patrol vehicle light color is blue rather than green.
- Japanese police use a flashing green light to signal an emergency vehicle much like the red lights used in North America.
- In Sweden, patrol vehicles flash either blue or white lights depending on the region and municipality.
- Some smaller US agencies may not equip their patrol cars with green lights due to budget constraints.
So while green is the predominant “on patrol” light color in American policing, local customs and practices in other countries lead to some variations worldwide.
Why Green and Not Another Color?
Given that red, blue, and amber lights predated the introduction of the green patrol light, why did policing agencies decide to add another color instead of using one of those? There are a few explanations:
- A new color was needed to distinguish patrol units from existing emergency (red) and urgent response (blue) lighting.
- Green is very different from red and blue wavelengths, making it stand out more clearly.
- Since traffic lights use red, yellow/amber, and green, it mirrors common driver expectations.
- Green is associated with safety and permission to proceed which matches the “active patrol” meaning.
- Studies showed green light reaches peak visibility at night compared to other colors.
- Green plastic filters were readily available for existing bulb technologies when standards were being set.
So the emergence of green as the preferred color for signaling active patrol status resulted from both technical considerations and a desire for a separate visual identifier that would have clear meaning to the public.
The Future of Police Green Lights
Looking ahead, there are a few ways we may see the police green light evolve with new technology:
- Transition to more energy efficient and durable LED lights rather than older incandescent bulbs.
- Integration of green lighting into futuristic vehicle designs with seamlessly integrated emergency lighting systems.
- Developments in “smart” directional lighting to concentrate illumination where most visible to the public.
- Powersaving features to automatically dim or turn off lights when a vehicle is stationary and idling.
- Enhanced remote activation capabilities to allow officers to control lights from outside the vehicle.
However, the basic purpose of the green “active patrol” light will likely remain an enduring feature of policing. The flashing green light on top of squad cars will continue to signify an officer’s on-duty status and presence protecting public safety.
Conclusion
The humble green police light plays an important role in law enforcement operations and public safety. While it doesn’t receive the same attention as the red and blue emergency lights, the green patrol beacon conveys a distinct message – an officer is on duty and monitoring the area. This flashing symbol of active police presence encourages safe driving, deters crime, and provides reassurance to the community. So the next time you see that green light steadily blinking above a squad car, know that it is there by design, serving a specific purpose and communicating an enduring statement: “Officer on Patrol”.
