Driving while intoxicated (DWI) arrests in Texas can have life-altering consequences. From license suspension to jail time, the stakes are high — and understanding how an officer builds a DUI case is essential for both drivers and legal professionals. At Lone Star Detectives, we've simplified this process into an easy-to-understand framework called the DWI Investigation Triangle, highlighting the three critical stages every lawful DWI arrest must follow in Texas.
The DWI Investigation Triangle: Three Pillars of a Lawful Arrest
This triangle illustrates the core components police officers must follow to make a DWI arrest that stands up in court:
1. Initial Traffic Stop
- 1.The foundation of every investigation begins with reasonable suspicion — a legal requirement that the officer must have a valid reason to stop your vehicle.
- 2.Common justifications include swerving or erratic driving, speeding or ignoring traffic signals, and equipment violations (e.g., broken taillights).
- 3.Legal Basis: Texas Transportation Code §543.001 and Terry v. Ohio.
- 4.Once stopped, officers observe for visible signs of intoxication like slurred speech, red eyes, the odor of alcohol, or admissions of drinking.
2. Field Investigation
- 1.If suspicion persists, the officer may ask the driver to exit the vehicle and begin a Standardized Field Sobriety Test (SFST) sequence. These NHTSA-approved tests include Horizontal Gaze Nystagmus (HGN), Walk-and-Turn, and One-Leg Stand.
- 2.Note: These tests are voluntary, although officers may not inform the driver of this fact. Results must be collected according to strict procedures to be valid in court.
3. Arrest and Chemical Testing
- 1.If probable cause is established — based on driving behavior, FST performance, and officer observations — the officer may proceed with a warrantless arrest under Texas CCP Art. 14.01(b).
- 2.The driver is then read the statutory warning (Form DIC-24), which outlines the consequences of refusing a breath or blood test under Texas's Implied Consent Law.
- 3.Refusing a test may result in automatic license suspension.
- 4.Officers may obtain a warrant to compel a blood draw if needed.
Quick Reference Summary
- A legal traffic stop must precede the investigation
- Field sobriety tests are voluntary and must follow standardized protocols
- Probable cause is required before an arrest
- Statutory warnings must be given before chemical testing
- Complete and accurate documentation, including video, is vital
Why This Matters for Defense Investigations
For attorneys and individuals facing DWI charges, understanding this triangle can uncover critical defense opportunities. At Lone Star Detectives, our investigators often find traffic stops lacking legal justification, improperly administered sobriety tests, violations of constitutional rights, and incomplete or inaccurate police documentation. When the state cuts corners, it can be the difference between conviction and acquittal.
Need Help Investigating a DWI Arrest?
At Lone Star Detectives, we support defense attorneys and private clients across Dallas–Fort Worth and all of Texas, offering expert investigative support that can expose flaws in the prosecution's case. Call today for a free, confidential consultation: 682-204-3041. Fort Worth, TX | Serving all of Texas.