In California, police can take a DNA sample from any person who is arrested on probable cause for a felony offense.
They cannot collect DNA samples from suspects arrested only on misdemeanor charges.
Police in all 50 states are currently empowered by law to take DNA samples from persons who have been convicted of a felony offense.
In 28 states, including California, police can collect DNA samples from suspects who have simply been arrested for a felony offense, even if they are never convicted of the offense.
California law enforcement agencies began collecting DNA samples from felony arrestees in 2004, when the practice was authorized through the passage of Proposition 69.
Proposition 69 requires that any person arrested for or convicted of a felony offense must submit to DNA testing.
The DNA sample is usually collected through a cheek swab. The police take the sample and submit it to a crime lab, where the DNA is amplified and then analyzed; creating a DNA profile that is unique to the individual who submitted the sample (the odds of another person sharing the same profile is extremely low, unless that person has an identical twin).
The suspect’s DNA profile is entered into a database where it can then be compared to millions of other DNA profiles derived from evidence found on victims, weapons, and crime scenes in thousands of offenses committed all across the country.
Citizens and civil libertarians have raised concerns that these DNA collection practices violate the privacy and constitutional rights of suspects.
However, courts have generally upheld DNA collection procedures like those that are used in California. In 2013, the U.S. Supreme Court upheld a similar procedure in the case of Maryland v. King. In that case, a man was forced to give a DNA sample after he was arrested on felony assault charges.
When his DNA profile was compared to other profiles in the national database, it was discovered that his DNA matched the DNA profile associated with evidence collected during a rape that had occurred six years earlier. The man was charged and eventually convicted of rape.
He appealed his conviction, arguing that his DNA sample was illegally obtained and therefore should have been suppressed. The state appellate court agreed and set aside his conviction.
However, the U.S. Supreme Court reversed that decision and held that the collection of DNA samples from suspects arrested for felony offenses did not violate the Fourth Amendment.
A federal appeals court in California recently decided a case involving California’s DNA collection practices.
In Haskell v. Harris, the U.S. Court of Appeals for the Ninth Circuit considered the claim of a woman who had been arrested for obstructing officers during a peace protest.
When she was arrested, she refused to submit a DNA sample and she sued the state. The Ninth Circuit court ruled against her and held that the DNA collection practice authorized by Proposition 69 was constitutional.
Defending Against DNA Evidence
Although DNA evidence can be very powerful, all is not lost for a suspect who is facing charges that are supported by DNA evidence.
An effective defense attorney can still identify arguments to support the suppression of DNA evidence, especially if the police acted illegally when they arrested the suspect in the first place.
If the police did not have probable cause to arrest the suspect, or if the police violated the rights of the suspect in order to obtain probable cause, then all of the evidence that followed from the improper police conduct should be suppressed, including the DNA sample.
Even if the DNA evidence was properly obtained, there are legitimate explanations for the presence of DNA at a crime scene, which should support a not guilty verdict.
For example, the suspect in Maryland v. King, whose DNA was linked to a rape victim, could still argue that his sexual contact with the victim was consensual.