While your implied consent in cooperating with blood, breath and alcohol testing is assumed by the state of New Hampshire, the state also assumes your implied consent in complying with the standard field sobriety tests that police officers have you perform in order to determine whether or not you are impaired by alcohol. Although it may result in the administrative suspension of your license, which you can later appeal, you should never agree to perform these tests. The results of these tests can only be problematic for you later, because even if your alcohol concentration level is below the legal limit, the police officer can testify about failed sobriety tests it at your hearing.
Field sobriety tests can include everything from being asked to touch your nose with the tip of your finger, to reciting the alphabet backwards and/or doing mathematical calculations. Do not do them! Do not be belligerent with the officer, but politely refuse to take the field sobriety tests.
Field sobriety tests are far too dependent upon one officer's subjective judgment and do not fully rely any kind of science. Your performance on these exercises may depend more on how tired you are or how coordinated you are rather than on how much alcohol you have consumed. There are circumstances under which you may not pass them even if you have had nothing to drink. Not only will the officer testify against you at a trial, but quite often a camera captures these tests on video (which is also admissible), and the evidence can be damning.
This post contains excerpts from The DWI Book, the definitive guide to protecting your rights in the face of New Hampshire's tough DWI/DUI laws.