[gone-ot]

...when the NATIONAL SAFETY COUNCIL presented its 'Driver Improvement Program' (ie: Defensive Driving Course) where I worked, this is the answer the presenter, an Arizona Highway Patrol officer, gave:

"...slow down, and let them pass."

...Why? Because the Arizona Revised Statutes (ARS) 28-704(c) has a "...five-vehicle back-up = pull over..." rule that originally pertained to farm vehicles and single-lane roads, but now states:

"ARS § 28-704 (c) states that "if a person is driving a vehicle at a speed less than the normal flow of traffic at the particular time and place on a two-lane highway where passing is unsafe, and if five or more vehicles are formed in a line behind the vehicle, the person shall turn the vehicle off the roadway at the nearest place designated as a turnout by signs erected by the director or a local authority, or wherever sufficient area for a safe turnout exists, in order to permit the vehicles following to proceed." Additionally, on multi-lane roadways, if vehicles approach and appear to want to pass, you should again signal and change lanes, proceeding to the right. Not only does awareness of safe driving procedures when traveling at slow speeds reduce the risk of a traffic collision, it also helps to avoid drivers possessed by road rage."

...lesson? Learn the "rules" for the state (and locality) you're driving through; and remember that "ignorance" is no justification (except for political offices)!