The latest debate on the death penalty seems to be turning less on moral issues than on practical ones. There is strong evidence that the system has not ensured that all persons on death row are actually guilty of the crimes for which they were convicted. This fact has been exposed by the rapid improvement in the tools for identifying and excluding rape and murder suspects. Five years ago, DNA tests could not link suspects to hair or semen found on a victim. Today a crime lab can identify unique DNA patterns in a tiny sample of just 100-200 cells. Until a procedure can be established to ensure that all death row cases have been subjected to such testing where possible, some States have placed a moratorium on executions. There are common elements in cases where errors have been made. These include when police and prosecutors are pressured by the community to "solve" a notorious murder; when there is no DNA evidence or reliable eyewitnesses; when the crime is especially heinous and draws large amounts of pretrial publicity; and when defense attorneys have limited resources. Some of the issues involved in challenges to the current application of the death penalty are questionable deterrence value, the prevalence of inadequate counsel, standards of guilt, and the costs compared to life imprisonment without parole.