Patrol Operations, Traffic, and Criminal Investigation
Patrol and traffic fundamentals
Patrol is the backbone of policing: visibility, deterrence, rapid response, community contact, and problem identification. Directed patrol and hot-spot strategies focus resources on identified risk. A traffic stop requires reasonable suspicion of a violation. Officers may order the driver out and passengers out for safety, but the stop's scope must remain tied to its purpose. A search requires probable cause, consent, or another valid exception; an inventory must follow policy and cannot be a pretext for a criminal search.
For DWI, know the three NHTSA phases: vehicle in motion, personal contact, and pre-arrest screening. Standardized field sobriety tests include horizontal gaze nystagmus, walk-and-turn, and one-leg stand. HGN is an indicator, not a direct measurement of blood alcohol. Implied consent means refusal carries license consequences and may prompt a warrant for a blood draw.
Investigation essentials
Initial response includes scene safety, aid, scene control, witness identification, evidence preservation, chain of custody, interviews, and report writing. Know common search patterns-line, grid, zone, and spiral-and the importance of contemporaneous documentation and body-worn camera review. Crash investigation requires protecting the scene, aiding the injured, documenting positions and conditions, and identifying witnesses.
Traps
Miranda does not automatically apply at a traffic stop. Consent can be limited or withdrawn. Inventory is not a search incident to arrest. HGN clues do not equal a specific BAC.
Worked example
A DWI stop: reasonable suspicion, stop, driving and personal observations, SFSTs, probable cause, arrest, statutory warnings, then test or warrant. Rule of thumb: document each decision point as if it will be challenged.