Traffic Law and Traffic Enforcement
Stops and enforcement
Traffic stops are the most common police-citizen encounter and are judged on legality, safety, and proportionality. Each stop needs reasonable suspicion of a violation or equipment defect; its scope is limited to that reason unless new facts justify expanding it. Minnesota enforces seat belt use as a primary offense and requires approved child restraints for young children, generally until age eight or a specified height.
DWI investigations
Minnesota prohibits driving with an alcohol concentration of 0.08 or more (0.04 for commercial drivers; zero tolerance for drivers under 21). Build the case in three phases: (1) driving (weaving, speed, lane violations), (2) personal contact (odor, eyes, speech, admissions), and (3) testing (standardized field sobriety tests, preliminary breath test, evidentiary test). Implied consent means an arrested DWI driver must be asked to submit to a chemical test and read the advisory accurately; refusing a breath test is itself a crime, and blood or urine generally requires a warrant.
Crashes
Minnesota requires a crash report when a crash involves death, injury, or property damage above the statutory threshold (currently $1,000). Secure the scene, render aid, identify witnesses, and photograph before vehicles are moved when it is safe to do so.
Trap: assuming consent to search a vehicle automatically follows from a lawful traffic stop, or that a citation is mandatory in every case-officers retain lawful discretion, but the articulated reason for a warning or citation must be consistent and non-discriminatory.
Rule of thumb: if you cannot state the violation in one sentence with specific facts, you may lack reasonable suspicion.
Worked example: You stop a car for 15 over. The driver fumbles for a license, speaks thickly, and admits to "a couple." That is probable cause for DWI; if the driver refuses testing, seek a warrant.