Two-second rule two seconds as inadequate, and recommend a three-second rule. German law requires a minimum 0.9 second distance but when tested under relaxed conditions researchers found that their test subjects spent 41% of the test time at following distances under 0.9 second. The United States National Safety Council suggests that a three-second rule—with increases of one second per factor of driving difficulty—is more appropriate. Factors that make driving more difficult include poor lighting conditions (dawn and dusk are the most common); inclement weather (ice, rain, snow, fog, etc.), adverse traffic mix (heavy vehicles, slow vehicles, impaired drivers, pedestrians, bicyclists, etc.), and
Rule of recognition if the rule of recognition were "what Professor X says is law", then any rule that Professor X spoke would be a valid legal rule. It follows that the rule of recognition is but a factual acknowledgement of what is indeed law; as per the classic illustration of a bill passed by the legislative authority and assented to by a Head-of-State. The fact that the bill has been made law in accordance with proper parliamentary procedure shall, in accordance with the Rule of Recognition, render it valid law. Again, this is primarily based on the fact of its existence in