In 2009, the Supreme Court ruled that "...prisoners do not have a constitutional right to DNA testing after their conviction... even though the technology provides an unparalleled ability both to exonerate the wrongly convicted and to identify the guilty." [1] In 2010, "a death row inmate waited an average of 178 months (roughly 15 years) between sentencing and execution... nearly a quarter of deaths on death row in the U.S. are due to natural causes." [2] Every case should be proved or disproved beyond a reasonable doubt with DNA evidence, as far as it is possible to obtain, and a special appellate court should be created to exclusively handle capital cases to ensure that the process from conviction to appeal to execution is just, swift, and humane.
[1] Washington Post. "Supreme Court Rules That Convicts Lack Constitutional Right to DNA Testing."
[2] Department of Justice: Capital punishment, 2010 statistical tables.