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Field sobriety tests in California: accuracy and legality

Jun 18, 2024 | DUI

Field sobriety tests (FSTs) are often a part of DUI cases because they are useful tools in DUI stops and investigations. Police officers use the tests to assess the state of a driver and gather evidence if they suspect that the driver may be under the influence. Given the role FSTs play as evidence, it is important to determine their accuracy and legality. 

Types of field sobriety tests

FSTs consist of three main tests: the Horizontal Gaze Nystagmus (HGN), the Walk-and-Turn, and the One-Leg Stand. Each test aims to assess a person’s balance, coordination, and eye movements by looking for the following signs:

  • Swaying
  • Trouble following instructions
  • Difficulty maintaining balance

These are often signs of impairment, but there are other factors that might result in these behaviors, such as extreme fatigue. These signs do not necessarily mean that the driver is under the influence.  

Accuracy concerns

One big issue with FSTs is their accuracy, which is important to keep in mind in DUI cases. Various factors can affect a person’s performance on these tests, including medical conditions, age, weight, and nervousness, all of which can cause someone to perform poorly. 

Legal considerations in California

The California Vehicle Code allows officers to use these tests as evidence in DUI cases. Drivers have the right to refuse to take them, such as if they have concerns about inaccurate results, but in some cases refusing FSTs might lead to arrest. This can prevent those potentially inaccurate test results from becoming evidence in a case against the driver. 

Protecting your rights in DUI cases

Despite the common use of FSTs in DUI investigations, their accuracy and legality are not without controversy. If you have concerns about field sobriety tests, it is best to know your rights and what the potential consequences are if you choose to take or refuse one.