California's "implied consent" law requires all drivers lawfully arrested for a DUI to submit to chemical testing to determine blood alcohol concentration (BAC) or the amount of drugs in the person's system. For an arrest to be lawful, the officer who stops you must have probable cause to believe you've been driving under the influence of alcohol or drugs. California law generally allows the driver to choose between a blood or breath test. But if neither a blood or breath test is available, the driver must take a urine test. (People who have hemophilia or are taking anticoagulants for a heart condition can't be required to take a blood test, but must, instead, submit to urine testing.)
An arresting officer is required by law to explain the consequences of refusing a test—that you'll be fined, lose your license, and face jail time if convicted of a DUI. The officer must also explain you don't have the right to speak to an attorney prior to taking the test and that a test refusal can be used against you in court.
Generally, the implied consent law doesn't require drivers to submit to a chemical test prior to a lawful arrest. However, to establish probable cause to make an arrest, an officer might ask you to take a voluntary "preliminary alcohol screening" (PAS) test. A PAS test is typically administered with a handheld breath test device (often called a "breathalyzer"). Only drivers who are under 21 years old or currently on DUI probation are required to take a pre-arrest PAS test.
The penalties for refusing to take a blood, breath, or urine test begin with a one-year license suspension. You could lose your license for two years for a second refusal or if you had a reckless driving or DUI conviction within the last ten years. The penalty jumps to a three-year suspension for your third refusal or if you have had more than one reckless driving or DUI conviction within ten years. The fine is the same—$125—whether it's your first, second, or third refusal.
The wisdom of refusing a post-arrest blood, breath, or urine test depends on the circumstances. And refusal may not help you avoid a DUI conviction—you can be found guilty even without BAC test results. In fact, the prosecution can argue to a jury that your refusal shows consciousness of guilt—that you refused to test because you knew you were intoxicated.
If you've been arrested for DUI in California or any other state, get help from an experienced DUI attorney. A DUI conviction—especially one involving physical injuries or repeat offenses—carries serious consequences. So your best bet is to find an attorney who knows the law and your local court system.