An extra reason to be cautious in your holiday driving:

If you live in one of 30 cities, you may find yourself pulled over soon at roadblocks where police and federal contractors ask to swab your cheeks, take your blood or give a breath sample to see if you’re on drugs without any probable cause that you’ve committed a crime. Such an exciting time for your civil liberties!

[Jalopnik via @ProfBainbridge] On the separate issue of “no-refusal” blood draws at DUI stops in states like Texas and Tennessee, see Sept. 30.

Filed under: Fourth Amendment, police, traffic laws