If not LE, rotating or flashing lights cannot be blue; which color is prohibited?

• A. red
• B. blue
• C. amber
• D. white

Answer: (B)

The main idea is that blue lights are reserved for law enforcement. Having rotating or flashing lights in blue signals an official police vehicle, so non–law enforcement vehicles are not allowed to display blue lights. That’s why blue is the color that’s prohibited for non-LE use in this scenario.

Other colors have legitimate uses for different emergency or warning purposes (for example, amber for caution/road work, red for various emergency services, and white for illumination or auxiliary lighting), but the rule highlighted here specifically targets blue because of its strong association with police.