DNA Identification: Applications and Issues (CRS Report for Congress)
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| Release Date |
Jan. 12, 2001 |
| Report Number |
RL30717 |
| Report Type |
Report |
| Authors |
Eric A. Fischer, Resources, Science, and Industry Division |
| Source Agency |
Congressional Research Service |
Summary:
DNA technology can provide useful identifying information in many situations, such as in
solving
crimes, determining paternity, and identifying human remains. Research is resulting in
improvements in sensitivity and power and reductions in cost. Such use and improvements are
raising several policy issues.
The use of DNA in identification results from its unique characteristics: It is a complex
molecule, containing much information. Each person has billions of identical copies. The structure
of the molecule varies from person to person and is inherited, so the DNA of relatives is more similar
than that of unrelated people. Also, DNA is easily preserved with the structure intact.
Identification requires comparing DNA whose source has not been determined with DNA
whose source is known. The first step is to characterize corresponding DNA sequences from
samples. The resulting profiles are then compared. If they differ, the samples did not have the same
origin. If they match, then they could have come from the known source, or from someone else who
has an identical profile. The science of population genetics provides ways of estimating
quantitatively the chances that the matched DNA could have come from another source.
Databases or indexes are often used in DNA identification. They might contain profiles of
persons whose identity is known, such as convicted felons, or whose identity is not known, such as
from crime scene samples or unidentified remains. The Combined DNA Index System (CODIS),
administered by the FBI, contains both kinds. When a profile is obtained from a relevant sample,
the database can be searched to determine if a match is found. Thus, a suspect may be identified
when a profile from a crime-scene sample is searched against profiles of convicted felons.
Congress has enacted several laws relating to DNA evidence. The DNA Identification Act of
1994 ( P.L. 103-322 ) authorized CODIS and a grants program for state and local laboratories, and
addressed quality control and privacy issues. The Antiterrorism and Effective Death Penalty Act of
1996 ( P.L. 104-132 ) expanded CODIS and established a grants program that required states, to be
eligible, to collect DNA samples from persons convicted of felony sex crimes. The Crime
Identification Technology Act of 1998 ( P.L. 105-521 ) established a grants program that funds a
broad range of activities, including several related to DNA typing. The National Institute of Justice
(NIJ) and the Bureau of Justice Assistance (BJA) administer those and other relevant grants
programs. The National Institute of Standards and Technology (NIST), the Armed Forces Institute
of Pathology (AFIP), and the Army Criminal Investigation Laboratory (USACIL) also have
significant DNA identification activities.
Policy issues raised by the use of DNA in identification include how best to eliminate the large
backlog of samples awaiting processing for CODIS, whether to broaden the offenses that qualify,
how to respond to the increasing number of requests for postconviction DNA analysis, how to
address privacy issues, and what impacts the broadening applications of the technology may have.
