Mario Rodriguez / Criminal Law Attorney

DNA Evidence: Is it Foolproof?

In 2004, the passage of Proposition 69 mandated the collection of DNA samples from all felons, and from adults and juveniles arrested for or charged with specified crimes, and submission to a state DNA database; and; starting in 2009, from adults arrested for or charged with any felony.
Last year, California began taking DNA upon arrest and expects to nearly double the growth rate of its database, to 390,000 profiles a year from 200,000.

The state is accumulating a statewide DNA database to be used to solve crimes. In order to solve crimes, the system will search for matches between database DNA and other profiles once a week, from now into the indeterminate future — until one day, perhaps decades hence, an arrestee might leave a drop of blood or semen at some crime scene.

Courts have generally upheld laws authorizing compulsory collection of DNA from convicts and ex-convicts under supervised release, on the grounds that criminal acts diminish privacy rights. Law enforcement officials say that DNA extraction upon arrest is no different than fingerprinting at routine bookings and that states purge profiles after people are cleared of suspicion. In practice, defense lawyers say this is a laborious process that often involves a court order. (The F.B.I. says it has never received a request to purge a profile from its database.) While many civil rights activists see law enforcement obtaining and filing this genetic information as a potential violation of privacy, others worry over the evidence for different reasons.

Dangers Associated with the Perceptions of Evidence
Some have warned that courts should be cautious in relying on DNA evidence. The problem with DNA is that if you get a match the evidence is so strong and compelling it almost guarantees conviction.

The idea that concerns many defense lawyers is that juries may begin to perceive that when DNA evidence is introduced into a court case it will encourage these men and women to ignore everything else presented. While DNA evidence has helped to better assure innocence or guilt in many cases, there is no evidence that it should be perceived as the absolute truth. Defense lawyers go to lengths to establish their own contexts into which each piece of evidence is explained and, like any evidence, its placement and purpose in the crime is something only the victim or perpetrator will ever know beyond a reasonable doubt.

Relying on Evidence a Consistent Fear as the Science of Detection Evolves
Concerns of evidence biasing juries is not a new concern in courtrooms. Whenever science uncovers a new way for detectives to approach crimes the new technology is often perceived as more incriminating than established methodology or evidence. Examples include items such as the polygraph or "lie detector." Oftentimes when a person submits to a polygraph and the results are found to be either inconclusive or detecting deception many assume this indicates guilt. However, the biological processes that the polygraph examines allow for errors not always associated with guilt. This is why polygraphs are inadmissable in courts unless ordered by a judge; they create a false sense of truth that can greatly damage juries ability to weight both sides of an issue.

The Ability to Fabricate DNA Evidence?
Last year, scientists in Israel showed that one can fabricate DNA evidence, calling into question the credibility of what has been considered the gold standard of proof in criminal cases.

Nucleix, a Tel-Aviv-based life sciences company, was able to create credible DNA evidence that could be used to finger the wrong person, proof that even genetic evidence can be manipulated (beyond planting a hair or used cigarette) just like other physical traces.

To make the fake DNA, all the researchers needed was a small sample of the DNA they wanted to plant (such as that from hair or lingering in saliva left on a discarded coffee cup) and blood from a donor. Donor blood was centrifuged to separate DNA-containing white cells and DNA-free red cells. The researchers then expanded the filched DNA into a larger sample size via whole genome amplification and added it to the DNA-free red blood cells from the donor. Blood that matched the genetic profile of the person to be framed—not the donor—was created.

Nucleix was also able to replicate a deceptive double helix just by working off genetic profiles in a police database. Building a small collection of common genetic variations—425—for different genome points, they were able to drum up a fabricated sample.

This development calls into question the presumed infallibility of this forensics golden child—by showing that it can be fabricated. Since we're creating a criminal justice system that is increasingly relying on technology, we need to examine the implications of fake DNA.