[Lurking Libertarian]

But it's okay to override the 4th Amendment to set up "safety" road-blocks to find the DUIs? WTF????

That's another whole line of cases, but, briefly stated, the distinction that's been drawn is that briefly stopping a car and making the driver roll down the window to see if he reeks of alcohol is much less intrusive than dragging the driver to a hospital and sticking a needle into his vein.

[Buckeye McFrog]

That was the rationale when they approved DUI checkpoints. But now they check your seat belt, your papers, whether you are driving with any unapproved child car seats with expired dates, etc. etc. etc. etc.

[oh8eleven]

making the driver roll down the window to see if he reeks of alcohol is much less intrusive
There is no probable cause - hence - the DUI "safety" stops are unconstitutional.
I ALWAYS tell this to the cops when I have to drive through them and the yget plenty pissed. I don't care.