By Byron Lichstein
There has been much attention paid recently, including in these pages, to a recent bill that purportedly heightens the admissibility standards for expert testimony.
Under the old standard, expert testimony in Wisconsin had to satisfy only a “relevancy” standard, meaning it was admissible if it would make the existence of any consequential fact more or less probable. Under that old standard, Wisconsin trial judges were not required to assess the scientific reliability of expert evidence as a prerequisite to admissibility. Under the new standard, such testimony must meet more rigorous scientific standards: the testimony must be based on sufficient facts or data and must be the product of reliable principles and methods.
There are many important potential consequences to this change, but one that has received little attention is the possible impact on wrongful convictions in criminal cases. It is now beyond dispute that various kinds of forensic science errors have played a significant role in wrongful convictions. Of the first 225 wrongful convictions overturned by DNA testing, more than 50 percent (116 cases) involved faulty forensic evidence that went undetected at the time of trial.
Based in part on these alarming statistics, Congress in 2009 charged the National Academy of Sciences with studying the strengths and weaknesses of the forensic sciences. That study produced a scathing critique, identifying widespread problems with the manner in which forensic science is conducted and presented in court. The United States Supreme Court, with Justice Scalia writing for the majority, joined this chorus in Melendez-Diaz v. Massachusetts, 129 S.Ct. 2527 (2009), citing wrongful convictions based on forensic science errors and stating bluntly, “Serious deficiencies have been found in the forensic evidence used in criminal trials.”
Wisconsin cases are typical of this trend. In the case of Robert Lee Stinson, for example, a forensic odontologist (bitemark expert) testified at Stinson’s 1985 murder trial that bitemarks on the victim’s body “had to have been made” by Stinson’s teeth with “no margin for error.” After 23 years of wrongful incarceration, a new bitemark analysis and DNA testing finally conclusively disproved this testimony, freeing Stinson and identifying the true perpetrator.
Stinson’s case demonstrates the essence of the problem with many of the forensic sciences: the odontologist’s claim of a conclusive identification has no basis in science. There is no empirical data demonstrating that bitemark experts can accurately match bitemarks to suspects’ teeth, nor is there any proof that two people with different teeth will necessarily leave identifiably different bitemarks in skin.
Nor is there reason to be sure that today’s forensic scientists have learned the hard lessons of cases like Stinson’s.
In a recent Wisconsin case, State v. Jones, 2010 WI App 133, a state crime laboratory analyst testified that a bullet found in the murder victim’s body had markings matching the defendant’s gun, that no other gun in the world could have left such markings, and that there was no error rate in the analyst’s analysis. Just like in Stinson’s case, there is no scientific basis for testifying to such a conclusive match. There is no data proving that ballistics experts can accurately match a bullet to a gun, that no two guns could possibly leave indistinguishable markings, or that ballistics analysis is an error-free method.
But on appeal, the Court of Appeals accepted the testimony, holding that Wisconsin’s (at that time) liberal admissibility standard barred the circuit court from excluding the testimony. The court contrasted Wisconsin’s standard to the more exacting standard in the federal system, established in Daubert v. Merrell Dow Pharmaceuticals, 509 U.S. 579 (1993). Following the decision allowing such unscientific testimony, the Department of Justice rejoiced, stating in a press release that “Murderers should fear forensic science.”
One might think that the advent of a Daubert standard in Wisconsin will mark the end of such unscientific testimony. Indeed, at least in theory, Daubert is intended to bring science into the courtroom, excluding expert testimony that has no basis in the scientific method or empirical data. But the reality is, in other states Daubert has not lived up to this theory. Instead, commentators have pointed out that criminal defense attorneys have too infrequently raised Daubert challenges, and judges have often rejected defendants’ Daubert challenges when doing so would risk weakening the state’s case against an allegedly violent offender. That trend in criminal cases has not held true in civil cases, where well-funded attorneys have appropriately raised Daubert challenges, and judges have rigorously applied Daubert to exclude unscientific evidence.
The point of all this would appear to be that Daubert will have an impact on wrongful convictions only if it is rigorously applied by defense attorneys and judges. Expert testimony that is exaggerated or unscientific can now be measured against a more rigorous legal test, one that at least has the potential to exclude expert testimony that has too-often had tragic consequences for innocent defendants. It is now up to Wisconsin attorneys and judges to ensure that Daubert lives up to its potential.
Byron Lichstein is deputy director of UW Law School’s Remington Center, a law-in-action program made up of several clinical projects dedicated to teaching, service, and research. He serves as director of the Criminal Appeals Project and supervising attorney for the Wisconsin Innocence Project.