Deputy Attorney General Rosenstein delivers remarks at the National Symposium on Forensic Science. (Photo: Courtesy of the Department of Justice)

Forensic science has been “under attack” in recent years—coming under fire for anything that doesn’t have a quantitative basis, Deputy Attorney General Rod Rosenstein told the National Symposium on Forensic Science on Tuesday.

But the quickly-evolving statistics of DNA forensics and other pursuits doesn’t mean that traditional trace evidence like fingerprints, shell casings and shoe marks are any less scientific, Rosenstein said, cautioning against an “erroneously narrow view” of forensic critics.

“Forensic science is not only quantitative or automated,” said the deputy attorney general. “It need not be entirely free from human assumptions, choices and judgments. That is not just true of forensic science. It is also the case in other applied expert fields like medicine, computer science and engineering.”

While there are attempts to amend Federal Rule of Evidence 702 to make it more instrument-based and automated, experience is key to expert testimony admission under the Daubert standard for American courtrooms, he said.

“Human observation, comparison, interpretation and judgment are core components of good science,” said Rosenstein, in his prepared remarks to the crowd of prosecutors and experts. “Some critics would like to see forensic evidence excluded from state federal courtrooms. You regularly face Frye and Daubert motions that challenge the admission of routine forensic methods.”

Rosenstein touted the use of “uniform language” when it comes to fingerprints testimony, as unveiled in February. Such language is intended to make clear how good a likely “match” is—by carefully avoiding words such as that without context.

In his speech, the second-ranked law officer in the U.S. also touted the activity of two new groups: the Council of Federal Forensic Laboratory Directors, and the recent forensic technology needs of state and local crime labs.

Rosenstein also pointed to breakneck new improvements in DNA, including rapid DNA testing and next-generation sequencing, as improving the ability of investigators to solve crimes by getting the right person, the first time. 

“As you hear about new scientific terms and learn about new forensic techniques, keep in mind that forensic science is a powerful tool that we must understand fully, use responsibly and defend appropriately, in order to satisfy our ultimate duties as prosecutors—to uncover the truth and pursue justice,” he said.

Such warnings to keep the important subjective forensic science in courtrooms has been a rallying cry for some of the scientists in the disciplines most attacked by critics since a watershed 2009 National Academics of Science report on the weaknesses of forensic science. Last year, Barry A.J. Fisher, a former president of the American Academy of Forensic Sciences and the former director of the Los Angeles County Sheriff’s Department Crime Laboratory, defended the reasonable and considered admission of traditional evidence.

“Not everything can be quantified,” Fisher has said.

In the meantime, the push for more quantitative standards continues. Mark Stolorow, the deputy director of the special programs office at the National Institute of Standards and Technology and the director of affairs for the Organization of Scientific Area Committees for Forensic Science (OSAC) reportedly said in an interview with Texas Public Radio at the International Association for Identification (IAI) conference last week in San Antonio that traditional techniques had not gone through “rigorous peer-reviewed scientific development” in the 20th century—and the process to change that through OSAC could take decades.

Correction: An earlier version of this story referred to a NIST official's comments being made to a crowd at last week's IAI conference. They instead were made in an interview with Texas Public Radio at the conference.