A potentially groundbreaking case regarding whether an alleged Stanford University serial killer's DNA is protected by privacy under the Fourth Amendment has been submitted by his defense attorneys to the California Supreme Court.

Attorneys for John Arthur Getreu, 75, who is accused of killing two young women on Stanford land in the 1970s, filed the request for the hearing before the high court on April 6. The case seeks to toss out DNA evidence collected from a discarded coffee cup that allegedly links Getreu to the crimes because police didn't obtain a warrant for the DNA evidence.

Under current law upheld in multiple court cases, police have the ability to collect evidence that a suspect throws into the trash or discards in a public place without a warrant — known as the abandonment doctrine. But new DNA technologies require the courts to revisit how the Fourth Amendment's right to privacy applies, defense attorney John Halley, who is representing Getreu in San Mateo County, said Tuesday. DNA evidence obtained by law enforcement can contain thousands of bits of personal information that are either not relevant to the case or that could be held and used in other circumstances — information that the person who tossed the item never intended to have made public, he said.

The implications of law enforcement gathering and preserving DNA evidence could have vast implications for the public, he said. Although police labs take only a small amount of the collected DNA that is considered "junk" DNA to identify a suspect, they retain the entirety of an individual's genetic material in perpetuity, he said. Halley is asking the state's high court to consider whether police should obtain a warrant for the DNA and show probable cause; any warrant should spell out what police can and can't use from the voluminous genetic information, he said.

His motion for a writ of mandate to toss the DNA evidence in Getreu's case has the support of the American Civil Liberties Union, which has sent the court an amicus letter. The national Legal Aid Society Criminal Defense also filed an amicus letter during the state's First Appellate District Court hearing on the case in May 2020.

After rejections from the appellate court and San Mateo County Superior Court, it's now in the state Supreme Court's hands to decide whether it will hear the motion.

Getreu, a Hayward resident, is charged with killing Leslie Marie Perlov and Janet Ann Taylor, both 21, on Stanford land in Santa Clara and San Mateo counties in the 1970s while he lived in Palo Alto. Perlov's body was found under an oak tree in the area of what is now the Stanford Dish in February 1973 and Taylor was found in a ditch off Sand Hill Road and Manzanita Way in March 1974. Both women were strangled.

The cases remained unsolved for more than four decades until 2018. Using new DNA technology and databases, such as those used to convict the notorious Golden State Killer, Santa Clara County sheriff's investigators accessed a commercial familial DNA database and obtained a DNA hit off evidence from the crime scene. Getreu was identified as a potential suspect.

Detectives followed Getreu during surveillance into a Kaiser Permanente pharmacy and watched him pick up a prescription, according to court filings. He discarded a coffee cup in the trash in the waiting area. Investigators collected the cup after he left the pharmacy. Laboratory staff extracted his DNA profile but used only a small segment that contained his identification information. It matched evidence found under Perlov's fingernails. Investigators obtained warrants to arrest Getreu for Perlov's murder and to collect a DNA cheek swab, also known as a buccal sample. He was charged with her murder in November 2018 in Santa Clara County. San Mateo County investigators also used the buccal sample to match Getreu to DNA found on Taylor's clothing. He was charged with her murder in May 2019. H awaits trial in both counties.

Jury selection in the San Mateo County trial was to begin on May 10. The trial has now been put on hold. If Getreu's attorneys are successful in getting the state Supreme Court to hear the case — and if the court rules in their favor — the ruling would also impact the case against Getreu in Santa Clara County, San Mateo County District Attorney Steve Wagstaffe said. It's also likely the case would go to the U.S. Supreme Court regardless of whoever loses, he added.

"They are trying to plow new ground," Wagstaffe said by phone on May 12.

The quest for a precedent

Prosecutors have argued that DNA extraction is not considered to be a "search," since the portion of DNA that is isolated and amplified to identify a suspect does not carry any information other than identification and doesn't infringe on a reasonable expectation of privacy. It's much like collecting fingerprints from a windowsill, which would not infringe on a privacy expectation, they have said.

But Halley argues that newer technology, including extraction of cellphone data and DNA evidence, requires a re-examination of Fourth Amendment protections. He likened the situation to a landmark 2018 case related to cellphone data, Carpenter vs. United States. The U.S. Supreme Court ruled the government's seizure of historical cellphone records — 127 days of phone-location data to identify a defendant's whereabouts — exceeded the amount of information needed to pinpoint his whereabouts on certain dates and times.

The government argued the Fourth Amendment inquiry should not focus on the entire seizure, but only on the subset of data actually used by the government. The state Supreme Court found the cellphone-data seizure was unlawful, however, because the entire set of data originally seized was so large that it violated a reasonable expectation of privacy, Halley noted.

"Just as the seizure of a full set of cell phone location data could not be defended on grounds that the government was selective in using only the portions relating to particular times and locations, so too here, the government’s seizure and extraction of defendant’s entire genome cannot be defended on grounds that the government was selective in amplifying and profiling only those portions that show identity. Since extracting the genome was actually done, and was necessary in order to do the subsequent identification analysis, that extraction of the genome must be justified," Halley wrote in his brief to the state Supreme Court.

"This genetic information is deeply private. It can reveal intensely sensitive information about us, including our propensities for certain medical conditions, our ancestry, and our biological familial relationships. Some researchers have also claimed that human behaviors such as aggression and addiction can be explained, at least in part, by genetics. … Our genetic blueprint must also be entitled to Fourth Amendment protection," he wrote.

This genetic material, which is shed constantly everywhere by everyone, is ripe for collection and abuse by law enforcement without a warrant, Halley noted during a May 18 phone interview with this news organization. Any argument that privacy protections were lost on the theory of "abandonment" is untenable in light of the unique nature of DNA, he maintained.

"The key notion of abandonment is that a defendant somehow took some action that made previously private information available to the government. But the government’s access to a sample of anyone’s DNA is not dependent on the person having done any act, other than simply moving through the world. People cannot avoid leaving their genetic data behind," he wrote to the court.

"People constantly shed staggering numbers of skin cells. The average person loses between 40 and 100 hairs per day. And a single sneeze can spew about 3,000 cell-containing droplets into the world. The simple act of touching an object leaves behind DNA. With every discarded coffee cup, crumpled tissue, plastic straw, cigarette butt, soda can, piece of gum and drifting flake of dandruff, people unavoidably and involuntarily leave a copy of their genetic blueprint," he said.

New technology requires new rules

The ACLU agreed with Halley. In its May 3 amicus letter to the state Supreme Court, its lawyers said, "If this Petition is denied, not only will California courts continue to ignore U.S. Supreme Court precedent requiring reevaluation of old Fourth Amendment rules in new technological contexts, but every Californian's entire genetic code — and all the private and sensitive information it reveals — will be vulnerable to collection search, and exploitation at the government's whim."

The question of a Fourth Amendment violation arises "because new technology has given the government a fundamentally new and unprecedentedly invasive surveillance power," they wrote.

The California attorney general's office, which is representing the county in its appeals, said there is a significant difference between the cellphone data and DNA, however.

DNA extract "is nothing like the product of 'tireless and absolute surveillance' performed when investigators tracked the cellular data," they wrote in their April 23 response to the state Supreme Court.

For the DNA identification, the laboratory performed "standard" short tandem repeat (STR) analysis using the polymerase chain reaction method; a "process that’s used in pretty much every government lab that does DNA analysis," the prosecution’s expert witness said during the lower court's hearing on the motion.

"While the testing process involved extracting the entire DNA molecule from cells in the DNA sample, the testing kit targeted 'junk DNA' and revealed less than one percent of the entire genome. The DNA expert drew an analogy to having 'an entire book from a library' but reading only 'one sentence,'" the Attorney General's Office quoted the expert in their response.

Getreu is asking the court to consider "a purely theoretical claim," the Attorney General's Office noted, which is not grounded in the facts of the case.

"The mere act of extracting DNA from cells deposited on an abandoned item, and maintaining possession of the resulting 'extract,' implicates no privacy interest whatsoever. For that reason, the extraction of DNA from cellular material lawfully possessed by the government was not a search or seizure for Fourth Amendment purposes," they wrote.

A government crime laboratory does not extract from a seized item a copy of the individual's genome, state prosecutors said. According to the National Institute of Health's National Human Genome Research Institute, a "genome" is the entire set of genetic instructions found in a cell.

Multiple state higher court cases have determined that extraction and amplification — the multiplication of the tiny segment of material used to identify a subject — "carry negligible weight on the privacy side of the equation in a Fourth Amendment balancing test," the Attorney General's Office wrote.

Wagstaffe said if the defense prevails, it could affect every case coming forward. If the state Supreme Court decides not to hear the motion, he's hopeful San Mateo County could try Getreu's case this summer. If the state Supreme Court decides to hear the case, there could be at least a two-year delay. Whoever loses will likely seek a ruling in the U.S. Supreme Court, which is likely to take the case given that it is a Fourth Amendment issue and is so novel, he said. The appeal could also go before the U.S. Supreme Court after Getreu's trial if the defense chooses to take it up after rather than before he is tried.