DNA can never be wrong, right? It is widely believed that DNA and other forensic evidence can unfailingly identify guilty criminals. But infallibility is simply impossible. Flawed scientific methods, structural obstacles and conflicts of interest can lead to fatal errors in forensics.
U.S. forensic labs are fragmented into local units, some serve entire states, others serve regions and some are run by police departments. What they all have in common is that they are not as strictly regulated and supervised as a lab at a hospital or university would be. In fact, many labs have been the subject of scandals in recent years, including drug thefts by lab employees, faking tests, lying about results, planting evidence, concealing errors, and failing to test evidence.
In one case, faulty scientific evidence helped to bring down the entire Houston police crime laboratory and call into question the very model of the modern crime lab. In a show-up, known as the least reliable identification procedure, George Rodriguez was identified as suspect by an abduction and rape victim based on „the way he stood.“ An analyst of the Houston Police Department Crime lab found his hair to be „consistent“ with a hair found in the victim’s panties and stated that Rodriguez could have left the stains found in the rape kit. At the same time, the analyst definitively excluded the defense’s suspect, Isidro Yanez. Although he had a solid alibi, Rodriguez was ultimately convicted and sentenced to sixty years in prison, while Yanez walked free. The analysis was however wrong. While Rodriguez could maybe not be excluded as suspect according to the blood analysis, so couldn’t Yanez and about any male in the population. After 18 years in prison, a new DNA test performed on the „consistent“ strand of hair confirmed Rodriguez innocence and led to his exoneration.
The Houston lab previously already had reported errors in DNA tests and had to shut down its DNA unit. With the scientific errors in the Rodriguez case coming to light, tens of thousands of hair and serology cases had to be reexamined and the city spent millions of dollars auditing the lab. The investigation of several years of the Houston lab’s work revealed that analysts sometimes faked tests. In fact, this malfeasance is so common that it has the nickname „drylabbing“. In other cases, defense attorneys were falsely told by the lab that there was nothing to test. In the wake of the audit, the lab was closed down.
The Rodriguez case also pointed to a conflict of interest when analysts work hand in hand with investigating officers at a police-run crime lab. The vast majority of crime labs are run by law enforcement and most labs will only test evidence if officers request it.
In 2012, the lab was reopened as the Houston Forensic Science Center, a new entity independent of the police that answers to scientists rather than cops.
But while independence can help to keep crime labs honest, it does little on behalf of justice if the lab techniques and scientific methods are questionable.
Problematic techniques include low-copy number DNA analysis (Read more), using DNA to locate suspects through their family members and testing people’s genes for predispositions toward violence and other behaviors and conditions.
Another problem are the statistics used in DNA database analysis (Read more). With ever expanding DNA databases, the chance of adventitious or coincidental matches increase. Moreover, the FBI recently even admitted basic math errors in the calculations of statistics used in tens of thousands of criminal cases.
There are also structural obstacles to overcome: Disproportionate policing of minorities, the vast majority of cases being settled with plea deals, crime labs being overwhelmed with DNA samples to process or public defenders lacking access to their own forensic expert.
Suspects and defendants lack rights to search DNA databases in order to prove their innocence since law enforcement „owns“ the DNA information. In many jurisdictions they do not have to be provided with detailed documentation of evidence by the police and prosecutors and lab analysts are not required to turn over their findings for defense scrutiny.
Ultimately, even a reform along the lines of Houston’s independent lab would not change the fact that police and prosecutors are bent on getting convictions. But the focus must not lie on quantity. Crime labs should not mass-process forensic tests, without adequate quality controls. Improving the quality of forensics will however require a cultural shift.
The good news is, that some labs are implementing new quality controls, more funding is being directed to basic research, and new scientific commissions are developing standards. Scientists, lawyers, judges, and forensic analysts are brought together to consider improved scientific standards, new research, and new procedures.
The question remains how much improvement better forensic standards really can yield? Human error can be minimized but is ultimately inevitable.
Source: Boston Review