Jan 23 2024

DNA in the Courtroom: Keeping Pace with Forensic Reform


Today’s guest blog is written by AnnaKay Kruger, Promega. Reposted from the ISHI Report with permission.


Grounded in empirical validation, DNA analysis is widely considered the gold standard of forensic science. In contrast, the perception of DNA analysts in the courtroom has undergone a noticeable shift over the years toward greater skepticism. In the early days of DNA forensics, expert testimony held significant weight, with, some argue, little critical scrutiny. More recently, the focus in court has changed, placing more emphasis on the methodological rigor and quality of forensic analyses over simply trusting the testimony of the analyst.


“There is no longer the sort of reverence afforded to expert witnesses when they walk into a courtroom like there was when I first got into it. Before, you were looked upon with reverence first, and then scrutiny. Now, you’re lucky to get the reverence,” said John Collins, former forensic laboratory system director for the state of Michigan and founder of the leadership coaching organization Critical Victories. He first testified in court in 1993. “I happen to think that’s reasonable,” he added. “I don’t think that you should be granted reverence that’s not earned.”


This paradigm shift has sparked debate about the respective roles and responsibilities of DNA analysts and other members of the court in ensuring the sound analysis, interpretation and presentation of forensic DNA evidence in criminal cases.


The CSI Effect

Increased confidence in the scientific standards by which laboratories analyze DNA, coupled with a deficit in the thorough understanding of how DNA analysis can be reasonably interpreted and applied, has led to new challenges for DNA analysts, who are called upon to effectively communicate the complexity of the science and the nuance of the analyses to a court system that some argue may rely too heavily on circumstantial DNA evidence to concretely prove guilt or innocence.


Tiffany Roy, forensic DNA expert and president of the forensic consulting agency ForensicAid, pointed out that, since the question of who is no longer routinely contested given the precision of the methodology, questions in the courtroom have shifted more to the how.


“The questions in court now are not so much about whose DNA it is—though that is an important question—but now revolve around how that DNA came to be there, and whether or not it was from innocent activity, or whether it was from a crime,” said Roy. “But we’re never going to know what happened at the crime scene. We weren’t there, and the appearance of the DNA profile doesn’t tell us those things.”


Forensic DNA experts seem to widely agree that the how cannot be determined by an analyst. However, the so-called “CSI-effect” and the empirical rigor of DNA analysis may lead those unfamiliar with the technology to incorrectly assume that DNA analysis represents a “smoking gun” rather than a single piece of supporting evidence in a larger case.


“I think attorneys will often ask about the activity associated with the DNA. There was [a suspect’s] DNA on the knife, therefore that knife had to be held by the suspect to stab somebody,” said Brian Kim, supervising criminalist in the Serology and DNA Unit of the Los Angeles Police Department. “That’s a bit of a leap, and, ideally, you would want a judge to confirm that that line of questioning is leading.”


From Crime Scene to Courtroom

Kim’s example illustrates how, in a courtroom, the presentation and interpretation of DNA evidence is a collaborative endeavor influenced by multiple key players, not solely the analyst. This interplay shapes how DNA evidence is communicated within the courtroom and subsequently understood by the jury.


In judicial proceedings, assuming DNA evidence is collected within the bounds of probable cause and is then properly handled and tested in an accredited laboratory following the appropriate protocols and procedures, a comprehensive report will be issued by the laboratory. This report will include what was tested, who tested it, protocols used and conclusions reached by the analyst. The report is then shared with the defense and evaluated for admissibility. If deemed admissible, the testifying expert will be expected to convey the findings and their significance to the court.


There are two sets of standards that courts use to determine whether DNA evidence is accurate, reliable, and thereby admissible. These are the Frye Standard, wherein the question of admissibility is delegated to the scientific community—admitting expert testimony so long as the methods for genotyping and interpretation are generally accepted within the scientific community to be sound—and the Daubert Standard, which upholds the Federal Rules of Evidence (in particular Rule 702) and identifies judges as gatekeepers, admitting expert testimony if the judge deems the expert qualified and the methods reliable. These are not uniformly applied across all cases and vary between states, though Daubert has largely surpassed Frye. However, there is debate over whether judges can reasonably be expected to “keep the gate” under Daubert given their lack of technical expertise. The answer to the question of where the responsibility truly lies, even beyond legalese, is fairly muddy among experts, but largely reflects that it is somewhat shared between the judge and the testifying analyst.


Julie Sikorsky, manager of the Forensic Biology Unit at the Palm Beach County Sheriff’s Office in Florida, explained: “The short answer is that both the judge and the scientists have a responsibility to make sure only scientifically valid and reliable evidence is presented in court. In reality, the ultimate responsibility does fall to the judge, as they are, after all, the gatekeepers. So we enter into this catch-22—while it ultimately relies on the judge to permit this evidence, it does trickle back down to, and is really only as good as, the testifying scientist.”


She added that, as a testifying analyst, the biggest challenge to bringing DNA evidence to court is ensuring that she can educate the triers of fact, be that the judge or the jury, enough to understand and appropriately contextualize the evidence she presents.


“I’m literally trying to teach them in a couple of minutes what it took me years of education, training and experience to learn, and expecting them to understand it, internalize it, and then apply it to what I’m presenting,” said Sikorsky.


She also points to the complicating fact that testimony from an analyst may then be restated, and sometimes misstated, by an attorney, affecting how that testimony is then interpreted by a jury.


“Once a scientist has left the courtroom, we have no control over that,” she said.



Cooperation and Accountability

So how can judges and analysts work together to ensure that DNA evidence presented in court is properly analyzed and appropriately contextualized in a criminal case? With the implementation of the Daubert standard, the influence of the judge as a gatekeeper is somewhat limited by their separation from the science, and while they may seek to educate themselves and glean insight from technical experts, their responsibility only extends as far as the requirements stipulated in Daubert.


“I think that the Daubert standard is a good standard for assessing evidence. Essentially you want to make sure that the methods applied are reliable, that they’re governed by standards that have been researched,” said Roy. “However, I think it’s important it be reliably applied to the facts and the data of the case. You could take a tool that’s totally valid and defensible, and you can still apply it to data to which it does not apply. You can take a chainsaw and perform brain surgery, but it’s not the right tool for the job, and so I think judges need to really be focused on each individual case and not necessarily precedent.”


Collins added that, beyond ensuring that evidence was analyzed with routine adherence to FBI quality assurance standards, judges could take extra care to prepare juries for forensic testimony by providing instructions prior to hearing an expert witness or allowing jury members to submit questions about the evidence.


“I think DNA is probably at the top of the list of the disciplines that would require this the most because it’s so complicated,” said Collins. “Providing them with good solid instructions before they hear evidence is going to be useful.”


For their part, laboratories should provide thorough written reports that communicate the limitations of the evidence and adequate training to ensure that their analysts do not inadvertently misrepresent findings in testimony.


DNA Analysis Down the Road

As methods and technologies evolve, broad oversight is necessary to ensure the continued maintenance of sound forensic DNA analysis. Roy voiced strong support for centralized, independent oversight, both on a state and federal level, and pointed to a report published by the National Academy of Sciences in 2009 recommending an essential oversight body. She cited the Texas Forensic Science Commission as an example of a state-level organization that establishes procedures, policies and practices to improve the quality of forensic analysis and provides a way to report and investigate possible negligence or misconduct in forensic laboratories.


Evolving technologies will also present new challenges for DNA analysts in the courtroom. Brian Kim mentioned that rapid advances in artificial intelligence as well as new methods like probabilistic genotyping, where mathematical models help determine the statistical weight of DNA evidence, may require analysts to adapt. Communicating uncertainty in forensic DNA analysis will become increasingly important as methods grow more precise, for instance, in the case of mixed sample analysis, which Roy asserts is far less clear cut than single-source DNA profiling.


“In forensic DNA, we went from, in the 90s and the early 2000s, making source attribution statements and identifying the person who left this DNA behind, to now, where as a field we’re recognizing that nothing in science is 100%,” said Roy. “We should just say what the data supports and what our statistics estimate and leave it at that. We shouldn’t try to make things seem like they’re foolproof. This is a human endeavor, we are just people doing this work, and people make mistakes.”


The shift in emphasis from expert testimony to scientific validation reflects a growing awareness of the need for transparency, accountability and adherence to scientific rigor within forensic science and legal proceedings. As the field continues to evolve, it is essential for the judicial system, forensic experts and policymakers to work collaboratively to address these complexities. DNA analysis remains a powerful tool, but its credibility and reliability must be upheld by those wielding it through ongoing scrutiny and adaptation to the changing landscape of forensic science.


Note: The views and opinions expressed by quoted sources are their own and do not necessarily reflect the official policy or position of their respective organizations.