First of all, a driver cannot lawfully be stopped if all his or her vehicle's equipment (lights, taillights, brake lights, license light, etc.) is working and no moving violation or infraction is committed - i.e. no speeding, no "California Roll" through a stop sign or right turn lane - or observed by a California policeman. However, if detained and suspected of DUI in California, all you are required to give is some form of (1) license, (2) insurance and (3) registration. DUI police are usually not on your side at this point, so pay attention carefully. It's better NOT to give police evidence that will be used against you in court. They're just trying to collect evidence so know your rights.
When you are questioned by a policeman (before arrest), you are NOT in custody for purposes of your Miranda rights and the California DUI cop's obligation to advise you so. Thus, when you politely refuse to answer the officer's questions relating to her or his California DUI investigation, either before or after the arrest, there will no be any statements which can thereafter be used against you in California court. Please remember DUI Field Sobriety Tests are optional in California. Even if you voluntarily try to these roadside acrobatics, you will probably be arrested in any event. Politely decline any hand-held breath test gadget aka a PAS or preliminary alcohol screening test. If you are more than 21 years of age, this PAS test is also voluntary so you have the right to refuse this type of breath test in the roads of California. When given a choice of blood, breath or urine test after arrest, choose a urine test if it is available as it is the most unreliable. The problem is, under current law, the officer may only offer a blood or breath test in California. If no urine test is allowed upon request, choose a breath test. Breath machines "estimate". They are not 100% accurate, reliable or trustworthy. Numerous possibilities for error exist throughout California. Ask to please call a spouse, parent, friend or relative from jail as soon as possible so they can hear you speak and note your state of sobriety. Upon release from custody, immediately consult with an experienced California DUI defense attorney.. Obviously, the preferred way to avoid a DUI conviction or California DMV suspension is to not excessively drink and then drive. Purchasing a Breath Tester may help estimate your alcohol level before you decide to drive. There are plenty of inexpensive Testers.