If an officer suspects you of driving under the influence, they cannot simply arrest you on the spot, even if they have a strong suspicion. Instead, they need to test your sobriety levels.
They have a variety of means by which to do this, including field sobriety tests. This is often their first line of testing, which means it would benefit you to have some familiarity with it.
Why are tests standardized?
VeryWell Mind discusses the place field sobriety tests have in an officer’s toolbox. Field sobriety tests come in two forms: standardized and non-standardized. The former sees more use, as they were technically invented to combat flaws in non-standardized testing. Primarily, the flaw came in the form of officer bias. Since the testing officer only had their own perception to go off of when judging whether a driver passed or failed, it left plenty of room for personal bias to color results.
Standardized tests supposedly help bypass this problem by introducing a standardized rubric used across the whole country. Because standardization is a relatively complex process, only three standardized tests currently exist. This includes the walk-and-turn, the one-legged stand and the horizontal gaze nystagmus.
What do these tests measure?
All field sobriety tests, whether standardized or not, serve to test several things about an individual. This often includes their concentration, dexterity, mobility, balance and ability to follow and understand instructions.
Officers will also likely keep an eye on your behavior and reactions to look for signs of intoxication or belligerence, which may contribute to the potential of your arrest. Thus, you should take any field sobriety test seriously, just as you would a breath or blood analysis test.