Sobriety checkpoints are legal in Missouri (see 755 S.W.2d 624 (Mo. App. 1988)). These checkpoints (also referred to as "mobile checkpoints" or "roadblocks") are police traffic stops that are not tied to any specific or individual suspicions.
Missouri's DWI implied consent laws require all drivers who are lawfully arrested for driving while intoxicated to take a blood, breath, urine, or saliva test. Read more about the law's specifics and the penalties for refusing to take a blood alcohol test.