What is the significance of recent court rulings addressing the admissibility of DNA evidence in the courtroom?
In the law enforcement world there is a long-standing practice of collecting DNA samples from already-convicted criminals and arrested suspects. Concerns over whether this practice violates suspects' privacy have escalated recently, leading to the upcoming February 2013 Supreme Court hearing on the case of a Maryland man being convicted of murder.
The collection and maintenance of forensic genetic databases has always been controversial. This controversy is becoming more heated because the samples in these databases will necessarily reflect the racial and economic disparities that are now widely recognized in studies on incarceration rates. This means that, for example, African-American men who were convicted of previous crimes and whose DNA samples remain in state custody may be at a higher risk of being suspected for subsequent crimes, simply because their DNA is available to the state for analysis. Those who are culpable retain their genetic privacy if law officers do not have samples of their DNA, while those who have or already serving time for their crimes may be suscepitble to having their DNA exploited when an investigation claims a possible "link" or "match".
However, and more to your question, the admissibility status of DNA in court cases isn't so much changing. Rather, how investigators handle the information the DNA evidence is changing. Take as an example the Amanda Knox case in Italy in 2007. Because the DNA evidence wasn't properly managed and carelessly neglected for long periods of time, the evidence was finally deemed to be unreliable as incriminatory. Knox's appeal was successful due to the weak DNA evidence linking her to the murder case.