It's a lengthy article, this is the abstract.
The 1996 U.S. Supreme Court decision Whren v. United States widened police officer discretion in making traffic stops. Prior to Whren, officers needed to be able to articulate “probable cause” about suspicion of drug activity if they made a traffic stop. Whren permits officers to make a pretextual stop, perhaps based on a very minor traffic infraction, that puts them in a position to better discern whether drug activity is taking place or not. As even the most cautious motorist regularly commits violations of heavily regulated traffic codes, officers can “legally” make a traffic stop on virtually every driver of whom they are even remotely suspicious. In a racially-ordered society such as the U.S., officers who consciously or unconsciously make race-based decisions about whom to suspect of criminal activity are now legally protected by the Whren decision. After years of public outcry about racial profiling practices in minority communities, the Whren decision is discussed in the context of recent studies showing evidence of racial profiling on our nation’s roadways, and the interesting turn mainstream criminologists have taken with their latest research concerning “perceptions” of being racially profiled. Data from a preliminary qualitative study of officer views on racial profiling is discussed.
BTW, what are your thoughts on the stop discribed in the first post. Given the directive sent out to law enforcement, was the bumper sticker a basis for reasonable suspicion? Or was the stop pretextual in nature?