If you drive a car in California you legally give your consent to have to a DUI chemical test of blood or breath, and sometimes urine, if suspected of "drunk driving."
California DUI police are required to inform a DUI suspect that his or her failure to submit to a chemical test will be considered a refusal, as well as the additional DUI penalties in Court and at DMV. The person accused of a California DUI must first be under lawful arrest by a California DUI peace officer who also must have reasonable cause to believe that the person is DUI.
The California DUI suspect has a choice of whether the chemical test will be of his breath or blood if accused of alcohol impairment, or blood, or urine if accused of impairment by drugs. Failure to submit to a test will result in the following penalties under California's implied consent laws:
A fine, mandatory imprisonment if the person is ultimately convicted, and suspension of the suspect's driver's license for a period of 1 year, 2 years if the refusal occurs within 10 years of a prior conviction or refusal.
If you cannot blow for some reason or cannnot provide a good enough breath sample upon being arrested for DUI in California, here's the law:
California's Vehicle Code states that if one is "incapable" of completing a test then he must submit to the other available test. VC §23612(a)(2)(A):
If the person is lawfully arrested for driving under the
influence of an alcoholic beverage, the person has the choice of
whether the test shall be of his or her blood or breath and the
officer shall advise the person that he or she has that choice. If
the person arrested either is incapable, or states that he or she is
incapable, of completing the chosen test, the person shall submit to
the remaining test. If a blood or breath test, or both, are
unavailable, then paragraph (2) of subdivision (d) applies.
Persons 21 or over do not have to blow in the hand-held California DUI breath test gadget, aka PAS test, but persons under the age of 21 are deemed to have given consent to a preliminary alcohol screening test and other chemical tests in DUI-related underage investigations.