The hearing is over for Adnan Syed, whose 2000 murder conviction came to national attention through the Serial podcast. The judge is now deciding whether the evidence presented at that hearing warrants Syed's request for a new trial. The request centers on two issues -- the alleged ineffectiveness of Syed's original trial lawyer Cristina Gutierrez in failing to contact a potential alibi witness, and alleged reliability issues with the cell phone evidence used to place Syed near the location where the victim's body was found.
Some background as to that second question -- using historical call records to trace a subscriber's location is a relatively recent development. The basic theory is that cell phones making or receiving calls will typically connect up with nearby cell towers, so tracking which towers were communicating with a particular cell phone during a given period can provide information about where that phone was during that period. It's been a controversial topic, with prosecutors and defense lawyers frequently sparring over the reliability of this type of evidence.
The issue in Syed's recent hearing centered on a fax cover page accompanying the original phone records. That cover page includes the following statement: "Outgoing calls only are reliable for location status. Any incoming calls will NOT be considered reliable information for location."
Abraham Waranowitz, the prosecution's expert witness at the original trial, now says he was never given that cover page before his testimony, and that he "consider[s] the existence of the disclaimer about incoming calls to have been critical information for [him] to address." He also says that if he had known about this, he "would have inquired further within [his] organization and attempted to learn why this disclaimer was issued."
That's an admirable admission, I suppose. But it raises a disturbing question:
If the level of his expertise was such that (a) he didn't know of a companywide position that an entire class of data was considered unreliable for the purpose for which he was using it, and (b) a boilerplate disclaimer on a fax cover page would have materially affected his conclusions, what the hell was he doing testifying as an "expert witness" on a critical issue in a murder case?
Waranowitz's admission highlights a widespread problem in the criminal justice system. In theory, an "expert witness" is someone with specialized knowledge who can help jurors understand complex evidence that they couldn't grasp as well on their own. Experts are integral parts of our criminal justice system, because a lot of the evidence that decides defendants' fates is genuinely complex. But there are serious risks associated with their testimony.
It's universally acknowledged that jurors (and judges) tend to give special deference to testimony from a supposed expert, on the theory that this person must really know what he's talking about (the substantive part of an expert's testimony usually follows an extensive discussion of his training, education, experience, etc.). If that deference is unwarranted, it can significantly distort the fact-finding process.
There are supposed to be safeguards in place at multiple levels to prevent this from happening. In theory, prosecutors themselves--"whose interest ... in a criminal prosecution is not that [they] shall win a case, but that justice shall be done" -- should be critically assessing these types of evidence before offering them in their trials. Judges are also supposed to act as "gatekeepers," screening out evidence whose actual quality doesn't support the weight it's likely to be given. And defense attorneys are supposed to highlight any weaknesses of the prosecution's forensic evidence so that jurors will be given an accurate overall picture.
In practice, these safeguards don't work as well as they should. Some prosecutors push the envelope, offering questionable evidence if it might support a conviction. Judges, who may lack confidence in their own abilities to critique complex evidence, tend to defer to prosecutors and their witnesses. And many defense attorneys are uncomfortable crossing swords with supposed experts.
The result is that defendants are regularly convicted based on supposed forensic evidence that turns out long after the fact to have been unreliable. Sometimes, like Mr. Waranowitz, the original experts attempt to excuse their initial testimony by saying they didn't know about their fields' limitations at the time. But if that's true, the lack of certainty regarding what the field could and couldn't prove should have been made known to the court. If there's genuine doubt as to whether a type of forensic evidence can reliably support the conclusions at issue, that evidence should be excluded -- or, at the very least, jurors should be specifically informed of its limitations.
These far-too-late mea culpas are happening far too often -- just within the past few years we've seen about-faces on supposed forensic evidence relating to arson determinations, microscopic hair comparisons, and "shaken baby" cases. I guess on balance it's a good thing that we're finally reassessing these types of evidence, but ideally the caution and humility we're now seeing would come a lot earlier in the process -- perhaps even before the expert takes the stand in a serious criminal case.