It's sometimes helpful when a dissent begins by quoting at some length -- and then responds to -- the majority opinion. Because that's a pretty concise summary of the justices' respective opinions.
For example, Justice Liu's dissent in this case begins by saying:
"According to today’s opinion, “[t]he sole question before us is whether it was
reasonable, under either the Fourth Amendment or article I, section 13 of the California
Constitution, to require the defendant in this case to swab his cheek as part of a routine
jail booking procedure following a valid arrest for felony arson.” (Maj. opn., ante, at
p. 41, italics added.) This statement of the issue is misleading.
The . . . (DNA Act)
requires collection of DNA from all adult felony arrestees “immediately following arrest”
and requires samples to be “forwarded immediately” to the laboratory for analysis. Buza was arrested on January 21, 2009. At booking a few
hours later, a police officer requested a cheek swab from Buza under penalty of law.
Buza refused. It was not until the next day, January 22, 2009, that a judge found
probable cause to believe Buza committed arson. On January 23, 2009, the district
attorney filed a complaint charging Buza with arson and related offenses as well as
unlawful refusal to provide a DNA specimen on January 21, 2009. The question is whether Buza can be convicted of refusing to provide his
DNA at booking prior to any judicial determination of whether he was validly arrested.
Today’s opinion does not explain why the fact that Buza was found “validly arrested on
probable cause to believe he had committed felony arson, and . . . was promptly charged
with (and ultimately convicted of) that offense” (maj. opn., ante, at p. 15) has any bearing
on whether it was lawful to require him to provide his DNA before any of those
determinations were made.
The court says that a “valid arrest” in this context does not require “a judicial
determination of its validity.” (Maj. opn., ante, at p. 23.) But this assertion, even if true,
does not disturb the main premise of the question presented: For purposes of
constitutional analysis, Buza is no different than any felony arrestee who has not been
charged, convicted, or found by a neutral magistrate to be lawfully detained. This point
is critical because it brings into focus the startling breadth of DNA collection and
retention authorized by the statute. This is not a scheme carefully calibrated to identify
felony offenders. Instead, it can be fairly described as a biological dragnet. As explained
below, and for the reasons stated in Justice Cuéllar’s dissent, the DNA Act violates the
prohibition on unreasonable searches and seizures in the California Constitution."
It's a 4-3 opinion. The majority upholds the statute. Which means that, in California, you're going to have your DNA taken upon any felony arrest. Regardless of what happens to you thereafter (and, as Justice Liu notes, one-third of people arrested for a felony don't ultimately get convicted of one).