If an officer has a reasonable, articulable suspicion that you have committed a DWI they may order you out of your vehicle, and ask you to conduct FSTs, and/or a PBT. These four roadside tests include, (1) Horizontal Gaze Nystagmus, (2) one-leg stand, (3) walk-and-turn, and (4) portable breath test.
It is important to understand that you have options. It is NOT a crime to refuse these roadside tests.  If you believe that there is even a chance that you are over the limit, you have nothing to gain from taking these tests. These test are unnatural movements, and failing the tests make your case much harder to win.

If you refuse the testing, the officer will likely arrest you anyway for suspicion of DWI. Likewise, if you fail the tests you will be arrested also. At this point you will be taken to the police station or hospital and read the Implied Consent Advisory. Refusing this blood, breath, or urine test IS A CRIME and can have significant consequences.

Every case is different. Exercise your right to speak with an attorney before making a decision about the Implied Consent testing.