They'll pick you out at the checkpoint, even if you are driving straight, and give you the full treatment. There is room for all kinds of abuse here.
Yea...if they're just picking every third car or something similar, then there are some rights issues.
Instead of checkpoints, they need to increase patrols in unmarked cars and then pull over obviously impaired drivers... (impaired can be drunk, texting or any other activity that causes you to drive stupid)
The checkpoint that they advertise in my area is just stupid. First they tell everyone...then it's in a spot that is easily navigated around by taking a couple of extra turns through a residential neighborhood. It's just a show of force...it's not actually deterring anyone or clearing the drunks off the street.