Texas DWI – 5 requirements of valid roadside and chemical testing

The officer must have had a reasonable suspicion that you were violating the law.
The officer must have either had probable cause to arrest you or obtain your consent for roadside tests.
The officer must inform you of your rights concerning a breath or blood test.
The officer must perform a 15 minute "observation period" before giving you a breath test
The proper chain of custody of your blood must be maintained.