In Birchfield v. North Dakota, the Court considered laws in effect in several states that make it a separate crime for people arrested for DUI to refuse DUI blood tests. The Court held that these laws are unconstitutional and that state governments may not require a DUI blood test without a warrant, even after a person is arrested.
But the Supreme Court also stated that this holding does not apply to DUI breath tests. According to the Court, breath tests do not involve the same Fourth Amendment privacy interest as blood tests.
So if you are arrested for DUI in California, and you refuse to take a DUI breath test, you may face additional penalties for chemical test refusal.
But note that these penalties do not apply to the preliminary alcohol screening (PAS) tests administered BEFORE you are actually arrested for DUI. You have the right to refuse this--and any other pre-arrest DUI screening test--without being penalized for doing so.