A third brake light, or center high-mounted stop lamp (CHMSL), is generally required on modern vehicles, and driving without a functioning one is often illegal in many places. Laws differ by country, state or province, and by the age of the vehicle.
In practice, the CHMSL exists to improve brake-light visibility and reduce rear-end collisions. While some very old vehicles may not be required to have a CHMSL, most newer cars are designed with this feature, and enforcement typically focuses on whether the lamp is present and functioning rather than the vehicle’s overall age. Always check your local regulations to be sure of the rules where you drive.
Regional overview
The following summaries explain how CHMSL requirements are commonly applied in major markets. For precise rules, consult your local department of motor vehicles or road authority.
United States and Canada
Key points about CHMSL requirements in the US and Canada:
- Federal safety standards apply to new vehicles and require a center high-mounted stop lamp on most passenger cars, SUVs, and light trucks.
- Vehicles manufactured after the standard’s effective date must have a functioning CHMSL; older models may not be federally obligated, but many states and provinces enforce that all required lighting works for public-road use.
- Police, inspectors, and safety tests can cite or fail vehicles with a non‑functioning CHMSL or with a broken brake-light system.
- Some imported or very early models may lack a CHMSL; retrofitting is sometimes allowed but not always required, depending on local rules.
Bottom line: In the US and Canada, if your vehicle was designed with a CHMSL and it’s not working, you can face enforcement action or a failed inspection. If your vehicle predates the CHMSL requirement, rules may differ by jurisdiction, so verify locally.
European Union and United Kingdom
Key points about CHMSL requirements in Europe and the UK:
- CHMSLs are generally mandatory on new passenger cars and many light commercial vehicles across the EU and the UK; they are checked during regular safety inspections (such as the MOT in the UK) and type-approval processes.
- A non‑functioning CHMSL can cause a failure in inspections and may lead to penalties if the vehicle is operated on public roads with defective lighting.
- Retrofit or replacement of a failed CHMSL is typically required to maintain roadworthiness.
- Older vehicles that never came with a CHMSL may be subject to different considerations, so local guidance should be consulted.
Conclusion: In Europe and the UK, a working CHMSL is expected on vehicles designed to include one, and driving with a failed CHMSL can lead to failures and penalties at inspection or roadside checks.
Other jurisdictions
Several other regions follow the same general principle: CHMSLs are common safety features on modern vehicles, and authorities expect them to be functional. As with other regions, some older or specialty vehicles may have exemptions or different retrofit requirements. Always verify with the local regulator if you are unsure.
- In many places, safety equipment rules require all required lighting to be maintained in working order.
- Non‑functioning brake lights can be cited as a safety violation and may affect vehicle compliance or registration.
Summary: Outside North America and Europe, the exact rule set varies, but the expectation is similar—a functioning CHMSL on vehicles designed to use one is typically required for lawful operation.
What to do if your CHMSL is out
If you discover your CHMSL isn’t working, here are recommended steps to take before driving again:
- Inspect simple causes first: check bulbs (if applicable), fuses, and wiring connections; some modern CHMSLs are LED modules that may be sealed and not easily user-serviceable.
- Consult your vehicle’s owner manual for the exact lamp replacement procedure and any fuse or relay locations.
- Visit a qualified mechanic or dealership to diagnose and repair; driving with a non‑functional CHMSL can be unsafe and may violate local laws.
- Consider testing the brake when a helper stands behind the car to verify the CHMSL illuminates when the brake pedal is pressed.
Conclusion: Don’t delay repairs. A working CHMSL is essential for safety and for staying legally compliant on public roads.
Summary
Across many jurisdictions, a functioning third brake light is a standard safety feature required by law for most modern vehicles. While rules vary by region and vehicle age, you should assume that if your CHMSL is present and required, it must work. If you drive a vehicle without a CHMSL or with a non‑working CHMSL, you risk tickets, failed inspections, and increased crash risk. When in doubt, check your local regulations and arrange prompt repair from a qualified technician.
Is a 3rd brake light required by law?
The federal government has required third brake lights on cars in the US since 1986 to improve the brake light's visibility.
Do you have to have your third brake light?
The third brake light was mandated in new passenger cars in 1986 in the US and Canada. The requirement was added to new light trucks and vans in 1994. Sometimes it's difficult to know if your third brake light is even working.
Can you drive with 2 out of 3 brake lights?
So if a 3rd brake light can be seen it must work. Third brake light is not a legal requirement whether it is fitted or not. As long as tail lights work you are covered.
Can I get a ticket for my third brake light being out?
You might think a burned-out third brake light is no big deal. After all, you've got two other brake lights. However, the reality is far different. Failing to fix the Center High‑Mounted Stop Lamp (CHMSL), the more official name, can lead to a traffic ticket, a failed inspection, or possibly an accident.