This is usually the number one question that people approach me with, upon finding out that I am a San Diego DUI Attorney. There are many people who have never had to go through this process and they simply don't know their rights. Here is a summary breakdown on what to do and not to do based upon sample questions if you are pulled over in San Diego and are investigated by the police for suspicion of DUI.
Do I have to answer their questions?
No. The only answer that you have to give them is provide them with your identifying information, including a driver license. Any answers that you give them regarding where you are coming from, what you have had to eat/drink will be written down in their police report and will be used against you to gain a conviction. You can politely tell the officer "I do not wish to answer any of your questions without a lawyer present."
No. Again, this is just voluntary information that you are giving the police officer to help him arrest you. These tests are extremely difficult to pass, even if you have not consumed any alcohol whatsoever. I have taken the same course that police officers take to conduct these tests based upon guidelines by (NHTSA) National Highway Traffic Safety Administration. There are only three nationally standardized tests that NHTSA recognizes: One Leg Stand, Walk and Turn and Horizontal Gaze Nystagmus. Even though nationally standardized, most of these tests are only shown to be accurate about 60% of the time. That is a scary percentage to think that you could be arrested for DUI if the tests are wrong 4 out of 10 times. Officers will try and get you to do other tests that are not nationally standardized, which are even less accurate than the NHTSA ones. The bottom line is, just answer "I am going to respectfully decline your voluntary tests."
Do I have to blow into that breath thingy?
Normally, its No if on the side of the road, or at the scene. The general of thumb is that you don't have to submit to any chemical test until the cuffs go on. The officers will try and get you to submit to an additional field sobriety test called a Preliminary Alcohol Screen device, or (PAS). This handheld breath instrument is also a voluntary test. You do not have to submit to it, UNLESS you are under 21 or on probation currently for DUI. If you are not one of those, the answer is "I am going to respectfully decline your voluntary test."
Do I have to submit to a chemical test after I am arrested?
Yes. In California, when you apply for a driver license, you sign an implied consent indicating that you will submit to a blood, breath or urine test after an arrest for suspicion of DUI upon request by a police officer. The officer must give you a choice of which test you prefer, unless there are exceptions. For instance, if you are in a remote area and no blood techs are available, or no breath machines available. This is rare and doesn't usually happen but there are always exceptions. The bottom line is yes, you must submit to a chemical test upon arrest or your driver license is subject to suspension for a year or more.
Should I do breath or blood?
9 times out of 10, you should always request a breath test. Blood is generally the most accurate because it is a direct draw of your arterial blood and shows amount of alcohol in your blood system already. A breath test is an sample of breath from your deep lungs and they use a calculation to determine what they think your blood alcohol level might be. The formula they use, called a Partition Ratio is 2100 ml of breath is equal to 1 ml of blood. They use this same ratio for everyone who takes a test, although some people may have a much lower Partition Ratio than others. For instance if someone has a Partition Ratio of 1300 to 1, then their breath sample may be overstated almost double what their true BAC is. Finally, the breath machine is just that. It is a machine and is subject to error. The bottom line answer is, choose a breath test.