When police pull you over, you'll be questioned. The officer may ask if you know why you've been stopped, if you know how fast you were going, and how many drinks you had. Answers could be used against you, to provide evidence you knowingly broke the law or to provide probable cause to conduct a blood alcohol concentration test. When you've been stopped, you obviously are not free to leave since fleeing the officer could lead to serious legal trouble. You have to stay until police give you permission to go.
Many people mistakenly believe answers to their questions at a traffic stop can only be used against them if they're read their Miranda rights. This is a common misconception from TV shows where defendants get evidence tossed out of court because they aren't read their rights. While evidence can be suppressed if police didn't give you a Miranda warning when required, a warning isn't necessary in all situations where police ask you questions.
An experienced DWI defense lawyer can provide assistance in determining if an officer violated constitutional protections and should have Mirandized you. If you weren't read your rights when you should have been, or if any Fourth or Fifth Amendment violation occurred, your attorney can motion the court to suppress the evidence. A prosecutor with insufficient evidence cannot prove guilt, and in some cases conviction for DWI can be avoided.
Do You Get a Miranda Warning At a Traffic Stop?
The Miranda warning is designed to ensure you understand constitutional protections. You must get a Miranda warning (i.e. be Mirandized or read your rights) before a custodial interrogation. If you don't get Mirandized, evidence obtained during the questioning can't be used by a prosecutor, nor can any evidence obtained as a result of things you said. Any evidence found as a result of an illegal interrogation is fruit of the poison tree.
When you've been stopped by the police and they ask you questions, you probably think you are being interrogated. Since you can't leave, you probably think you are in custody. The Supreme Court disagrees. A holding in Berkemer v. McCarty established the rule that police don't have to Mirandize you before questioning you at a traffic stop because the "atmosphere surrounding an ordinary traffic stop is substantially less "police dominated"' than it was in the Miranda case or than it is in other situations where you are officially "in custody."
Questions police ask when you've been stopped are just a preliminary investigation - but anything you say can be used against you, even if you don't get warned about that first. Be polite, but remember you don't have to provide all the answers the officer is hoping to get from you.
When an officer decides to arrest you for drunk driving, you officially get taken into custody. This triggers the Miranda warning requirement. If police don't tell you your rights at this time, an argument can be made to exclude answers to further questions asked.