Four major scientific organizations have asked the U.S. Department of Justice to institute an independent committee to look at the “scientific and technical gaps” in forensic science.

Their letter, dated Friday, is in response to the Department of Justice’s call for public comment about the state of forensic science, in the wake of Attorney General Jeff Sessions’ disbanding of the National Commission on Forensic Science in April.

The American Association for the Advancement of Science, the American Chemical Society, the Federation of Association in Behavioral and Brain Sciences and the Human Factors and Ergonomics Society write that Sessions and the top federal law enforcement authorities in the country should have outside scientists assessing the reliability of American crime-solving.

“We simply do not know whether many forensic practices are reliable or valid scientifically, and in some circumstances forensics practices are demonstrably unreliable,” they write. “Yet the results of many of these forensic disciplines continue to be commonly used as evidence in our courtrooms.”

The NCFS served the vital function, the science groups contend, and there should be a similar independent federal advisory committee to provide direct advice to the AG, the DOJ and federal laboratories.

Independence from prosecutors and vested interests is key, they add.

“The importance of independence from DOJ in this endeavor cannot be overstated,” they write. “The DOJ must not be put in the position of using forensic tools in its role as a prosecutor in federal criminal litigation, while simultaneously determining the scientific value of those same tools.”

The NCFS was one of the linchpins in the “forensic overhaul”—the reconsideration of much of forensic science, from the empirical evaluation of evidence to how it is presented in courts. Such reconsiderations truly kicked off in 2009, with the major National Academy of Sciences report titled “Strengthening Forensic Science in the United States: A Path Forward.” That report blasted some established practices, including hair analysis, bitemarks and eyewitness testimony.

Another report, by the President’s Council of Advisors on Science and Technology (PCAST), was released late in September 2016 and similarly criticized the use of some disciplines in forensic science. The two reports bookended the Obama administration. President Donald Trump has pledged support to law enforcement nationwide in his first few months in office, and Sessions quickly disbanded the NCFS just weeks after being sworn in.

The NCFS produced 45 documents and recommendations in three years of work, which encompassed 600 public comments.

The implementation of some of those recommendations continues with the Organization of Scientific Area Committees for Forensic Science, known as OSAC. Split into dozens of subcommittees of forensic experts, OSAC continues to meet and evaluate the state of forensic science. The latest set of written standards were released last month, and all 560 OSAC members from its 34 committees and subcommittees, plus an additional 100 subject matter experts, convened at in-person meetings in Virginia back in April.