California law says that police officers SHALL inform subjects that they aren’t required to take FST’s or breathalyzers prior to arrest.
(i) If the officer decides to use a preliminary alcohol screening
test, the officer shall advise the person that he or she is
requesting that person to take a preliminary alcohol screening test
to assist the officer in determining if that person is under the
influence of alcohol or drugs, or a combination of alcohol and drugs.
The person’s obligation to submit to a blood, breath, or urine test,
as required by this section, for the purpose of determining the
alcohol or drug content of that person’s blood, is not satisfied by
the person submitting to a preliminary alcohol screening test. The
officer shall advise the person of that fact and of the person’s
right to refuse to take the preliminary alcohol screening test.