Combined DNA Index System

Examples of these databases include, missing persons, convicted offenders, and forensic samples collected from crime scenes.

[1] The FBI's strategic goal was to maximize the voluntary participation of states and avoid what happened several years early, when eight western states frustrated with the progress creating a national Automated Fingerprint Identification System (AFIS) network formed the Western Identification Network (WIN).

[2] The FBI's strategy to discourage states from creating systems that competed with CODIS was to develop DNA databasing software and provide it free of charge to state and local crime laboratories.This strategic decision--to provide software free of charge for the purpose of gaining market share--was innovative at that time and predated the browser wars.

(Some in the Bureau believed the Act was not required to establish a national DNA database because the FBI's Criminal Justice Information Services Division was already using similar authorities to provide data-sharing solutions to federal, state, local, and tribal law enforcement agencies.)

The DNA Identification Act also required that laboratories participating in the CODIS program maintain accreditation from an independent nonprofit organization that is actively involved in the forensic fields and that scientists processing DNA samples for submission into CODIS maintain proficiency and are routinely tested to ensure the quality of the profiles being uploaded into the database.

Today, all 50 states, the District of Columbia, federal law enforcement, the Army Laboratory, and Puerto Rico participate in the national sharing of DNA profiles.

[8][9] Unidentified remains are processed for DNA by the University of North Texas Center for Human Identification which is funded by the National Institute of Justice.

[13] The bulk of identifications using CODIS rely on short tandem repeats (STRs) that are scattered throughout the human genome and on statistics that are used to calculate the rarity of that specific profile in the population.

At each location tested during DNA analysis, also known as a locus (plural loci), a person has two sets of repeats, one from the father and one from the mother.

Partial profiles are also allowed in CODIS in separate indexes and are common in crime scene samples that are degraded or are mixtures of multiple individuals.

[12][24] Note that even in states which limit collection of DNA retained in the state database only to those convicted of a crime, local databases, such as the forensic laboratory operated by New York City's Office of Chief Medical Examiner, may collect DNA samples of arrestees who have not been convicted.

The collection of arrestee samples raised constitutional issues, specifically the Fourth Amendment prohibiting unreasonable search and seizure.

[26] The inheritance pattern of some DNA means that close relatives share a higher percentage of alleles between each other than with other, random, members of society.

[28] This practice also raised Fourth Amendment challenges as the individual who ends up being charged with a crime was only implicated because someone else's DNA was in the CODIS database.