The UC Davis Legal Studies Research Paper Series recently released an article entitled Revising State Post-Conviction Relief Statutes to Cover Convictions Resting on Subsequently Invalidated Expert Testimony by former Army JAG, and prominent evidence law scholar, Professor of Law Emeritus Edward J. Imwinkelried. The article posits:
Invalid expert testimony has become a disturbingly recurrent theme in the wrongful conviction studies.
Id. at 3.
To remedy this situation, the article proposes that a statutory remedy ought to be created by which an accused convicted upon invalid expert opinion testimony might obtain a new trial:
It is submitted that an accused ought to be entitled to a new trial when: (1) the accused presents testimony about a new analytic technique developed in subsequent scientific research; (2) that technique yields a different outcome than the expert technique used at the prior trial; and (3) the validation of the new technique is so extensive that it either discredits the prior expert testimony or seriously undermines confidence in its correctness. The Constitution may not mandate a new trial in these circumstances. However, the American criminal justice is intensely concerned about the reliability of the evidence it relies on to justify convictions, and the proposed general standard operationalizes that concern.
Id. at 17.
After proposing his solution, Professor Imwinkelried’s article describes some of the practices which have given rise to the problem of invalid expert opinion testimony in American criminal trials.
First, the article notes that “[i]n a disturbing number of cases, postconviction investigation has revealed that witnesses called as experts have misstated—usually overstated—their credentials.” Id. at 19. By overstating their credentials, the article argues, those experts mislead the finder of fact to accept their opinions with less skepticism than would be directed towards a lay witness, or a less qualified expert.
The article also spends a good amount of time exploring the ways in which experts too often rely upon invalid presumptions or discredited methodology to reach their conclusions. But, one particular expert fallacy receives a bit more of Professor Imwinkelried’s attention:
Statements suggesting or implying greater certainty are not scientifically valid and should not be permitted. In particular, courts should never permit scientifically indefensible claims such as: “zero,” “vanishingly small,” “essentially zero,” negligible,” “minimal,” or “microscopic” error rates; “100 percent certainty” or proof “to a reasonable degree of scientific certainty;” identification “to the exclusion of all other sources;” or a chance of error so remote as to be a “practical” impossibility.
Id. at 25, quoting Report to the President – Forensic Science in Criminal Courts: Ensuring Scientific Validity of Feature -Comparison Methods, President’s Council of Advisors on Sci. and Tech. (2016) at 19. The article explains further:
The basic tenet of metrology is that no measurement is certain. No matter how carefully the analyst conducts the measurement and no matter how well calibrated the measuring instrument is, the analyst can never be certain that he or she has captured the true value of the measurand.
Id. at 26. The scientifically-sound way of presenting a scientific conclusion is to make sure it is articulated as an estimate accompanied by a confidence interval. Id.
The last section of Professor Imwinkelried’s article focuses on why current means of obtaining post-trial relief are insufficient when science is found to be shoddy after the trial is over. The difficulty is particularly prominent in the military justice system where there are no standing trial courts for an accused to seek post-trial relief from. Instead, military defendants must rely upon direct appeal – which may not even be available depending on the severity of the adjudged and approved sentence. Even if direct appeal is available, the standard for obtaining relief tends to be prohibitive. The extraordinary writ process is even more restrictive – not merely by its exceedingly high standard for obtaining relief, but also because the military appellate courts have a very narrow jurisdiction. Accordingly, the article recommends a statutory regime which would allow new trials in deserving cases where improper scientific evidence was permitted to slip pass the gatekeeper.