From the moment an officer pulls you over on suspicion of driving under the influence, his or her sole mission is most likely to gather enough evidence against you to establish probable cause for an arrest.
Once an officer believes that you may be intoxicated, it's difficult to overcome that bias. This means that every interaction with and observation by the officer from this point will be tainted with the belief that you are drunk. One area where you don't have to help the officer out is when it comes to field sobriety tests.
You don't have to do it
The first thing you should know is that you don't have to submit to field sobriety tests, but officers won't tell you that. In fact, if you decline to take the tests, officers may attempt to guilt you into complying. They may tell you that taking the tests will convince them you aren't intoxicated, but even sober people fail field sobriety tests. Officers may tell you that if you had nothing to hide, you would take the tests.
These types of statements are designed to get you to agree to participate in field sobriety tests. You may calmly refuse. If the officer persists, then you may ask to speak with an attorney. The officer may deny this request, and you may end up under arrest regardless of whether you submit to field sobriety tests.
The results rely heavily on the officer
Whether you fail a field sobriety test often lies within the subjectivity of the officer giving the test. He or she has at least some bias against you already since there is a suspicion of impairment. The officer may not even be aware of it, but it will more than likely influence the outcome of the tests.
However, the officer's perceptions and judgment are not the only factors that could result in you failing a field sobriety test. Many other factors could contribute to that such as your age, medical condition or physical condition, among other things, at the time of the tests.
As you can see, the odds are against you when it comes to taking field sobriety tests. Even if you had nothing to drink, you could end up failing these tests and end up under arrest. Approximately one third of all sober people who submit to these tests fail them. If you don't participate in the tests, at least the officer can't use them to establish probable cause that you were drunk driving.