Most people think officers always need a reason (reasonable suspicion of atraffic offense) to stop a moving vehicle. However, this Labor Day weekend some cities and towns in Illinois and beyond will use a sobriety checkpoint to briefly detain and interview suspicious drivers. You can learn more about when and where these checkpoints or roadblocks will be instituted by checking www.roadblock.org or www.duiblock.com.
These roadblocks are extremely controversial. You can read more about Sobriety Checkpoint here: http://www.chicagotribune.com/suburbs/lake-county-news-sun/opinion/ct-lns-rutter-dui-checkpoints-st-0515-20150514-story.html