New York Times

Week in Review

March 16, 2003

 

 

You Think DNA Evidence Is Foolproof? Try Again

 

By ADAM LIPTAK

 

DNA recovered in a 1998 carjacking and rape case in Houston matched that of Josiah Sutton, a 16-year-old defendant, according to a report from the Houston Police Department's crime laboratory. Mr. Sutton's DNA profile, the report said, "can be expected to occur in 1 out of 694,000 people among the black population" in the United States.

That evidence, supplemented by questionable testimony from the victim, led a jury to convict Mr. Sutton in 1999. He was sentenced to 25 years, but was freed on Wednesday after retesting of the DNA excluded him as a suspect.

DNA testing, when properly conducted and interpreted, can provide categorical proof of guilt or innocence. Its role in the exoneration of more than 120 people has captured the public imagination. But this uniquely authoritative tool can also play a role in wrongful convictions.

"It is powerful evidence both to convict and to exonerate," said Peter Neufeld, a founder of the Innocence Project at Cardozo Law School, a program that works to free innocent people in prison. "It's kind of a truth machine. But any machine when it gets in the hands of human beings can be manipulated or abused."

On Tuesday, Attorney General John Ashcroft announced the administration's plans to commit $1 billion to DNA testing in the next five years. Part of the money would be devoted to testing for felons who claimed to be innocent, but most would be used to address a growing backlog of forensic evidence from crime scenes and to expand the national DNA database.

Elizabeth A. Johnson, an expert in DNA testing in California, said everyone in the criminal justice system should be wary of accepting reports concerning DNA evidence without testing their conclusions.

"It is very, very reliable if you do two things right: if you test it right, and if you interpret the results right," Ms. Johnson said. "The problem is that jurors think it's absolute and infallible."

The problem with DNA testing is not that it results in falsely positive results. The problem is the human factor.

"So many of the people who give DNA testimony," said Stephen B. Bright, the director of the Southern Center for Human Rights, "went to two weeks of training by the F.B.I. in Quantico, say, and they are miraculously transformed from beat policemen into forensic scientists."

The analyst who testified in Mr. Sutton's case said she had attended a two-week training course sponsored by the company that sold DNA kits to her laboratory.

Her unit, which legal experts said was the worst of any major American city until it was shut in January, helped convict scores and possibly hundreds of defendants. A state audit in December found that it routinely mishandled evidence and exaggerated its significance. The audit prompted prosecutors to vow to retest available DNA evidence in every case in which it had been used to obtain a conviction or guilty plea. Mr. Sutton was the first defendant exonerated by the retesting.

Even before the new testing, independent experts said a proper analysis showed that the DNA in Mr. Sutton's case matched 1 of 8 black people, not 1 of nearly 700,000.

But DNA tests performed for the prosecution are seldom reanalyzed. "Defense lawyers, like everyone else, have become so convinced of its infallibility that they don't bother to challenge it," said William C. Thompson, a professor of criminology at the University of California at Irvine.

Judges will not authorize payments for retesting, said Harlan Levy, a New York lawyer who has worked with DNA evidence as a prosecutor and a defense expert and is the author of "And the Blood Cried Out," an analysis of such evidence in the justice system. Testing costs $2,000 to $4,000.

"If you have had a test done by a qualified crime lab," Mr. Levy said, "no court is going to order that a second test be done at government expense."

Dr. Johnson said even innocent defendants are swayed by DNA evidence. "Quite often defendants are intimidated into taking a plea," she said.

And even people seeking to overturn wrongful convictions, like David Dow, director of the Texas Innocence Network, have viewed DNA reports prepared for prosecutors as conclusive.

"It is a whole new chapter in DNA exonerations," Professor Dow said, describing how the Sutton case has caused his group to revise its process for deciding which cases to accept. "When we used to review a case, if there was a DNA test done and a scientist testified there was a match, we wouldn't take the case. There are certain assumptions all the players make. One is that when scientists in the crime labs test evidence, their testing is reliable."

Timothy Fallon, director of the Bexar County crime laboratory in San Antonio, told a committee of the Texas Legislature this month that there was only one way to assure the integrity of DNA testing by laboratories.

"Resources must be made available to criminal defense attorneys," he said. "If you want the best crime lab,you need to have the best criminal defense attorneys to challenge us."

Mr. Levy cautioned that the Houston experience was atypical.

"Overwhelmingly, there is not a problem," he said. "But giving defendants the resources to have scientists give a second look at the evidence and make suggestions about what problems there might be and their significance, would be useful. This is complex science."

The exonerating power of DNA evidence reveals the unreliability of other forms of incriminating evidence.

"In something like one-quarter of DNA exonerations, there was a confession," Professor Dow said. "In something like three-quarters, there was an eyewitness."

AS a consequence, legal experts say, such testimony in cases without DNA evidence should not be given much weight. In fact, DNA may have raised the bar on what qualifies as acceptable proof of innocence. Defendants and inmates in cases without biological evidence can have a very difficult time trying to establish their innocence.

Mr. Neufeld estimated that biological evidence that can be subjected to DNA testing to identify the guilty is available in fewer than 10 percent of violent crimes. "DNA exonerations create the illusion that we can really have a foolproof system of justice," Professor Dow said. "That's quite false."