This is a more recent appellate ruling that explains the legality of DUI checkpoints from the Gerschoffer ruling. We call it the Gerschoffer test.
http://www.in.gov/judiciary/opinions/pdf/07251201ewn.pdf
So, if the State determined that illegal drug activity is a threat to public safety, based upon what I am reading, what would stop them from putting all of the addresses in a random area in a hat, draw a few out and conduct searches of those houses? Or selecting a neighborhood from a hat and searching every house in the neighborhood? The courts are no longer the defenders of the Contitiution and the people's rights that they are supposed to be. They seem more interested in determining ways to enable the government by rationalizing the violations of rights.