[ossiblue]

Rick has pretty well covered this issue in his posts, but to address the OP's original question (where is the 5th?), the answer is buried in the procedures.

(Using California law as example). As stated by Rick, you do not have to submit to a field sobriety test prior to your arrest and the police must advise you of that. Your refusal, prior to arrest, cannot be used as evidence in court and cannot be the reason for a subsequent arrest. If you are arrested, it must be due to some other factor that led the officer to probable cause. This procedure is the 5th amendment protection against self-incrimination. The FST gathers evidence, as stated in other posts. You cannot be forced to give evidence against yourself (5th amend.) thus, you can refuse the request to test, prior to arrest.

Once arrested, the game changes, and you must submit. You cannot demand an attorney to advise your about submitting to a test. Refusing the test at this stage can be used as evidence in court.