[Nifster]

Because they told the driver it was voluntary. They asked her to pull into the parking lot area for a voluntary program

DUI checkpoints are identified as such. If they are looking for a bad guy in the car (i.e. a road block) they tell you so.

[JRandomFreeper]

She signaled that she wanted to go straight ahead, and the uniformed (off-duty) police officer wouldn't let her pass, and forced her into the parking lot.

That's unacceptable.

She said it certainly didn't feel 'voluntary'.

/johnny