In California, and any other state, the Fourth Amendment of the Constitution deems any search and seizure to be illegal unless there's probable cause for it to occur. When you're issued your driver's license in California, however, one of the documents you sign is a consent form to have your blood, urine or breath tested by police. This implied consent law is only enforceable if you're already been placed under arrest though.
Even then, in recent Supreme Court rulings, the panel has continued to err on the side of upholding protections afforded to citizens under the Fourth Amendment. Therefore, while a police officer can advise a motorist of the penalties he or she faces by not submitting to requested testing, in the absence of a warrant, any forced submission may be seen as unconstitutional.
If an individual is placed under arrest on suspicion of drunk driving, then a police officer may be given more leeway in asking him or her to submit to testing. They are, however, limited in options to either a breath or blood test.
Provided that the person they're arresting is conscious, they're required to give him or her a chance to pick between the two as well. Urine testing is only taken if the others are not available. An officer may also unilaterally request a blood test if dual intoxication from both drugs and alcohol is suspected.
In instances in which an individual is not conscious or deceased, they are still subject to California's implied consent laws.
California law also allows for a suspected drunk driver to not be afforded an opportunity to speak with an attorney before deciding whether to take a test. State law also allows for a defendant's refusal to submit to testing to be used against them in court.
Prosecutors are allowed to do this because one of the ways officers generally obtain probable cause is by having the suspected intoxicated driver complete a Breathalyzer test first. Depending on the results of that test, a defendant is asked to submit to blood or urine testing to confirm their intoxication.
Those who are charged with driving under the influence (DUI) risk being assessed high fines and lengthy jail sentences depending on how badly intoxicated they were and other aggravated factors. If you've been accused of drunk driving, then a Van Nuys DUI defense attorney can advise you as to the penalties you face in your respective legal case.
Source: ABC 10, "What are your California rights when police request a blood test?," Alexa Renee, Sep. 01, 2017