The innovation of DNA technology in criminal justice cases has revolutionized the relationship between science and capital punishment. No longer are executions or exonerations totally reliant upon unreliable eyewitnesses or dubious alibis; rather, a single hair or drop of blood can condemn or free an individual facing the consequences of a terrible crime.

DNA History
The discovery of DNA (deoxyribonucleic acid) can be traced to the work of numerous scientists and researchers over hundreds of years.

Entire areas of scientific knowledge and technology were made possible by the discovery and development of DNA technologies. Modern medicine or correct human anatomical knowledge is not conceivable without DNA. Even cloning, for better or worse, owes its existence to DNA.

Criminal Justice Applications
The criminal justice system has only been the latest field to be rocked by advances in DNA technology. In the past decade, forensic science, relying heavily on DNA identification, has become a leading factor in criminal cases and has become particularly crucial to death penalty sentences and exonerations. As courts and governments around the country recognize the rising importance of DNA evidence http://www.mdpd.com/astmhtm.html, DNA “fingerprinting” has taken on a role in most capital punishment cases.

Every person has a different combination of “base pairs” in their DNA. Analyzing the sequence of the base pairs, DNA fingerprinting can determine whether two DNA samples are from the same person, related people, or non-related people. Scientists use a small number of sequences of DNA that are known to vary among individuals a great deal, and analyze those to get a certain probability of a match. Therefore, DNA isolated from blood, hair, skin cells, or other genetic evidence left at the scene of a crime can becompared with the DNA of a criminal suspect to determine guilt or innocence. Patterns are also useful in establishing the identity of a homicide victim, either from DNA found as evidence or from the body itself.

Problems With Patterns
Like nearly everything else in the scientific world, nothing about DNA fingerprinting is 100% assured. http://www.biology.washington.edu/fingerprint/problems.html The term DNA fingerprint is, in one sense, a misnomer: it implies that, like a fingerprint, the pattern for a given person is utterly and completely unique to that person. Actually, all that a pattern can do is present a probability that the person in question is indeed the person to whom the pattern (of the child, the criminal evidence, or whatever else) belongs. A probability might be 1 in 20 billion, which would indicate that the person can be reasonably matched with the DNA fingerprint; then again, a probability might only be 1 in 20, leaving a large amount of doubt regarding the specific identity of the pattern's owner.