This was, and is, the level where impairment is usually readily discernable. It was adopted to expedite the arrest and conviction of drivers who do not necessarily exhibit visible levels of impairment. It is the DWI equivalent of the 55 mph speed limit. Lowered BAC levels serve to intimidate casual and social drinkers and give the police unbridled discretion to test and arrest almost anyone who has been drinking. Sobriety checkpoints are police roadblocks and that is what we will call them, police roadblocks.
Police roadblocks are symbolic and characteristic of police states.
They should be anathema to any person with an historical perspective of how authoritarian governments exercise control over their citizens. Roadblocks are meant to intimidate and restrict the movement of people, goods, and ideas. No free society should tolerate any precedent that rationalizes the use of roadblocks. When the U.S. Supreme Court approved the use of roadblocks for DWI enforcement, they opened a Pandora's box of abuses. The Court addressed the issue solely from the DWI perspective.