the purpose of these checkpoints is to get/keep drunk drivers off the road. they are random (they check every so many cars...not the ones they suspect of being drunk), and at least at the ones around here, they look at your license, but don't check for warrants and such (they way they would if they pulled you over for speeding).
I'm very much in favor of revising the immigration laws....documentable and legal ways for people to come into the country to work, harsh penalties to employers who hire illegals knowingly or without reasonable precautions, law enforcement enforcing immigration laws when someone is detained, something more unplesant than being fed, detained, and returned to Mexico for repeat offenders.
I see a lot of value in not having the illegals that are here under our current system be afraid of casual encounters with law enforcement. How could they report a crime? How could they provide evidence of a crime?
Again, this only applies to the sobriety check points....not to a driver that is pulled over for having a tail light out.