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
Chatham House Rule so that better international relations may be achieved. The rule is now used internationally as an aid to free discussion. The original rule of 1927 was refined in October 1992 and again in 2002. Chatham House has translated the rule into Arabic, Chinese, French, German, Portuguese, Spanish and Russian. The rule is a contrast (or a compromise) between private meetings, where revealing what was said in the meeting is forbidden, and "on the record" events where the discussion is completely public and attributed. Generally, the Chatham House Rule is imposed as a condition of being allowed to attend a meeting