In addition to administering a PBT, police will ask you to conduct what are known as Standard field Sobriety Tests (SFST), which test your performance in conducting physical tests to measure your level of intoxication. Police rely upon their subjective observations, unlike the PBT, to determine whether there is probable cause to arrest you on suspicion of drunk driving.
The police will utilize several different tests including the Horizontal Gaze Nystagmus (HGN), Walk and turn (WAT), One-leg Stand (OLS), Finger-to-Nose, and the Romberg Balance. All of these tests are based on police observations and meant to determine whether you look and act drunk and give the police reason to arrest you.
I know the common mistakes to look for in the administration of the field tests and will attack them to ensure your rights are adequately preserved.