Everyone knows the drill when the police pull someone over under the suspicion of DUI. They ask the driver to step out of the vehicle and perform tasks to determine their level of intoxication. The three field sobriety tests drivers are most often asked to perform the walk-and-turn, the one-leg stand, and the horizontal gaze test.

What you may not know is that these tests are not entirely accurate. There are some studies that show just how ineffective these tests can be. Today we are going to explore the history and accuracy of field sobriety tests.

The History of Field Sobriety Tests

In 1975 the National Highway Traffic Safety Administration (NHTSA) gave the task of standardizing field sobriety tests to the Southern California Research Institute. Up until that point, every police department had different tests. The goal of the study was to find the most accurate tests and make them the national standard.

SCRI took a look at 16 different tests that police departments nationwide were using. The test had to determine if a driver’s BAC was greater than .10% not that they were under the influence. In the end, the researchers choose the walk-and-turn test, the one-leg stand test, and the Horizontal Gaze Nystagmus test (HGN).

The walk-and-turn test is exactly what it sounds like. A driver has to take nine heel to toe steps in a straight line, turn around, and take nine heel to toe steps back. In the one-leg stand test, a driver elevates one foot six inches off the ground while counting by one thousand until the officer tells them to stop. Lastly, the HGN test involves a driver following an object with only their eyes, back and forth.

The Accuracy of Field Sobriety Tests

Upon conclusion of the study, the SCRI put officers to the test. Officers had to determine the level of intoxication of a participant with only the help of the three tests. So what were the results? The officers got it right with about the same frequency as they would have had they flipped a coin. There was a 47 percent margin of error. Researchers attributed the poor test results to officers not scoring the tests properly and ignoring evidence that showed some impairment was from factors other than alcohol.

The test results were so bad that the NHTSA had the institute conduct them again in 1981. After six years of training police officers, you would think the tests would be extremely accurate. However, the results still weren’t great. The HGN test could correctly identify someone with a BAC over .10, 77 percent of the time. The walk-and-turn test was accurate 68 percent of the time. Lastly, the one-leg stand test was correct 65 percent of the time. However, in combination, these tests were correct 80 percent of the time. The authors noted that there was a 32 percent false arrest rate.

These tests are far from perfect and result in countless false arrests for DUIs every year. The tests are especially inaccurate when performed by people over the age of 65, are more than 50 pounds overweight, or that have back leg, or middle ear problems. So, as you can see these tests do not accurately predict someone’s BAC in many cases.

Should You Take Field Sobriety Tests?

The short answer is no. Field sobriety tests are not a requirement. However, police officers receive training to make it seem like you don’t have a choice. You can politely decline to take the field sobriety tests. Taking the tests can only give an officer more probable cause to arrest you. If an officer pulls you over for a DUI, it is probably best to not take the tests.

The same is true for a portable breathalyzer device. These devices are only a tool to increase probable cause; they can’t be used in a court case against you. You can politely decline to take a portable breathalyzer. However, Massachusetts has what is called implied consent. This means that if you have a driver’s license, you give your consent to submit to a chemical test. This only applies to more accurate tests like those administered at the police station or a hospital. If an officer still places you under arrest after not submitting to any roadside tests, it may be best to submit to the chemical testing. If you do not your license will be immediately suspended.

The last thing you should do if a police officer pulls you over under suspicion of DUI is to remain silent. Under no circumstances should you admit to drinking. Telling the officer that you had one drink hours ago instantly gives them probable cause. Respectfully state that you are exercising your right to remain silent.

If you are facing DUI charges, contact an experienced Massachusetts DUI attorney today.