“The question this case presents is the extent to which technology can be permitted to diminish the privacy guaranteed by the Fourth Amendment.” So writes a California appellate court, in invalidating the part of the California DNA Act which requires automatic DNA testing of people arrested for felony offenses.

Under Proposition 69 – an amendment to the DNA Act approved by California voters in 2004 – the police must take a swab from the inner cheek of every person arrested for a felony offense. Even people who haven’t been convicted of a felony offense, even people who haven’t been convicted of a misdemeanor offense, even those who end up not being charged with anything, have to give a biological sample for DNA testing.

The court denounced the argument of the Attorney General that a DNA sample is required only for the purpose of identifying arrestees, holding that rather “What the DNA Act authorizes is the warrantless and suspicionless search of individuals, before a judicial determination of probable cause to believe they have committed a crime, for evidence of crime unrelated to that for which they have been arrested.” Because that broad intrusion is unreasonable in relation to the governmental interests, it violates the Fourth Amendment.

The court distinguished DNA sampling from, say, fingerprinting, which is a routine part of the booking process. A vast amount of private information is encoded in our genes. While the California DNA Act does contain legal safeguards on the use and analysis of the biological material, the biological sample itself is not destroyed. So the government is essentially sitting on a trove of personal information.

The court’s bold decision in People v. Buza that as applied to people who merely stand accused, the DNA Act violates the right to privacy, represents a resounding victory for the presumption of innocence and the right to privacy.