Feb 18, 2009

Update: Crime Labs Remain Under the Microscope


After a lengthy study, the National Academy of Sciences has called for a thorough overhaul of the nation's crime labs. (To read the Academy's news release, visit their website.)

The report described a sort of "sliding scale" of forensic reliability. The most reliable types of lab tests are "objective" and are based on biological or chemical analysis. DNA analysis is at the top of the scale; its results are consistently reliable. (Unfortunately, what the report does not say is that many DNA labs are so backlogged that statutes of limitations often expire before testing can be carried out.)

Reliability problems crop up when crime lab analysis rests on "subjective" factors.  Fingerprint, bitemark, toolmark, and similar experts perform their work through subjective interpretation of their samples -- largely in the absence of national standards and protocols.  In many cases, the basic principles and techniques underlying a field of forensic expertise have never been formally studied or established.  Moreover, the labs that carry out the tests often work for police and prosecutors (raising issues of impartiality), and their operations are often haphazard with uncertain quality control.

The report may impel judges to take their "gate-keeping" role more seriously. Instead of allowing forensic experts to testify because "we've always allowed these kinds of experts to testify," judges may require prosecutors to demonstrate that a field of expertise has been subjected to analysis and has been shown to be reliable.

Apart from what happens in court, the report may also encourage all levels of government to invest in our nation's crime labs.  As matters stand now, it's hard to be confident that forensic test results are reliably identifying the guilty and freeing the innocent.