 Sergeant Darisse then began following Vasquez.Vasquez eventually slowed his car when approaching a slower-moving vehicle, and Sergeant Darisse observed the car's right rear brake light hadn't turned on.Sergeant Darisse believed that it was a violation of North Carolina traffic law to drive a vehicle with a broken brake light, so he activated his blue lights and stopped Vasquez (observing that as he did so, the right brake light "flickered on").