In analyzing the legality of a traffic-related arrest, there are two important factors. First, the stop must be legal. To be legal, the police must have some reason to believe you violated a New York traffic law. If the officer says, for example, you crossed the yellow line or you were driving recklessly, then this threshold is likely satisfied. If, on the other hand, the police are not able to provide a reason for the stop, then the stop and subsequent arrest is illegal. This situation, however, is quite rare. One reason is because, in practice, police could give practically any reason and it will be upheld so long as you do not have proof the officer was lying. If the incident was tape-recorded it is possible that this could refute the officer’s account.
After establishing the legality of the stop, the police must establish the arrest was supported by probable cause. Probable cause could be established by your own statements or even the manner in which you answered the officer’s question. Unfortunately, police often say things like “I will let you go if” in order to extract statements that could establish evidence of your guilt. The tactic puts people at ease and also plays to the perception that police are trustworthy.
It seems likely if the tests came back with zero percent alcohol level, the officer’s would have let you go. As far as your question is concerned regarding whether police must show you the results before arresting you, the answer is there is no such obligation. However, police must submit evidence showing you did commit the offense you were charged with.
The best course of action is to consult with a criminal defense attorney in Buffalo, Ny as soon as possible.