Obtaining DNA Sample Before Conviction

The Fourth Amendment prohibits unreasonable search and seizures by the police. While some warrantless searches are permitted based on the circumstances, there must be some reasonable and articulable suspicion by a law enforcement officer before a person may be detained, and searched. The consequences for an unlawful search can be significant including the suppression of all evidence that were a product of the unlawful search.

Police, however, are permitted to conduct a search when it is incident to an arrest. The reason for this is to prevent the defendant from destroying evidence or to ensure the defendant does not have a weapon that may be a threat to the arresting officer. Upon arrest, police are further permitted to take mug shots and obtain fingerprints.

Recently, court cases across the country have challenged state and Federal laws that allow police to also obtain DNA samples from persons arrested, but not yet convicted of felonies. Twenty-eight states have laws that allow for the taking of DNA samples prior to a felony conviction. The first such law was passed in Louisiana in 1997 and allowed for DNA samples to be taken from any person arrested for a felony sex offense or other specified offense. In 2009, a California law took effect which requires law enforcement officers to obtain a DNA sample by swabbing the inner cheek of every person arrested for a felony. The information is then entered into a national database.

Proponents of such laws argue that DNA samples are necessary to assist law enforcement with identification of suspects of other crimes, and that submitting DNA samples are no more intrusive than fingerprints or strip searches, which have been held to be constitutional. Moreover, guidelines are implemented to ensure that the genetic information obtained is used only for authorized purposes.

On the other hand, critics of these laws point out that once DNA samples are submitted, the data is stored regardless of whether the suspect is eventually convicted. In California, for example, approximately 300,000 people are arrested for a felony each year, yet almost 100,000 are never convicted or even formally charged; yet their genetic information has already been submitted and stored in a national databases.

The U.S. Supreme Court is expected to rule on the issue this fall in light of split decisions by Federal courts across the country. For example, the Maryland statute allowing for pre-conviction DNA samples was held unconstitutional, while a similar law in California was upheld. While state law varies, the major aspects of each law are:

  • which offenses are included?
  • when is the DNA sample collected and when is it analyzed?
  • who collects the sample?
  • what protocol is followed for collection and analysis?
  • what process is available for expungement?

Surprisingly, DNA technology has only been used since 1985. Since then, DNA technology has become the most reliable source of physical evidence in criminal cases, particularly those involving sexual assaults. Forensic testing of genetic material can match DNA found at a crime scene with the perpetrator with better than 99% accuracy. DNA evidence has also been used successfully to exonerate the innocent. To date, 300 of convictions have been overturned on the basis of DNA testing, including over 100 for people who were on death row.