Bite-Mark Analysis: Junk Science or Just A Few “Bad Apple” Practitioners?

Of all of the methods studied in the 2009 National Academy of Sciences’ report on forensic science, forensic odontology — the analysis of bite marks to identify the perpetrators of crimes — has come under some of the harshest criticism.  And now an effort is underway to keep it out of courtrooms for good.

This article by the Associated Press examined “decades of court records, archives, news reports and filings by the Innocence Project in order to compile the most comprehensive count to date of those exonerated after being convicted or charged based on bite mark evidence.”   Typically, the evidence consisted of testimony by forensic dentists identifying marks on the bodies of victims (usually in cases of murder or sexual assault) as coming from the defendant’s teeth.  According to the AP, since 2000, DNA identification has overturned one after another of these cases, throwing the entire “discipline” into question, and rendering it nearly obsolete.

Critics make two main claims against forensic odontology.  First, there’s no scientific proof that a bite mark can be matched to any particular set of teeth.  There is no data, no experimental evidence — nothing — on which to base the idea that forensic odontology can make reliable identifications.  Second, human skin — almost always the site of the bite mark in question — does not reliably “record” bite marks, since the skin itself changes over time, even after death.  Because the skin changes shape, consistency, color, and even size  after the mark is made, this makes bite marks, and the method itself, inherently unstable.

Yet the dentists, who belong to the American Board of Forensic Odontology, insist that their methods of making identifications of the source of bite marks are reliable; it’s just that some forensic dentists are, well, not too good or biased.  ”The problem lies in the analyst or the bias,” said Dr. Frank Wright, a forensic dentist in Cincinnati. “So if the analyst is … not properly trained or introduces bias into their exam, sure, it’s going to be polluted, just like any other scientific investigation. It doesn’t mean bite mark evidence is bad.”  It’s the familiar refrain: it’s just a few bad apples, not the whole barrel.  But according to the AP:

Only about 100 forensic dentists are certified by the odontology board, and just a fraction are actively analyzing and comparing bite marks. Certification requires no proficiency tests. The board requires a dentist to have been the lead investigator and to have testified in one current bite mark case and to analyze six past cases on file — a system criticized by defense attorneys because it requires testimony before certification…The consequences for being wrong are almost nonexistent. Many lawsuits against forensic dentists employed by counties and medical examiner’s offices have been thrown out because as government officials, they’re largely immune from liability.  Only one member of the American Board of Forensic Odontology has ever been suspended, none has ever been decertified, and some dentists still on the board have been involved in some of the most high-profile and egregious exonerations on record.

It’s worth noting that there’s nothing wrong with other uses of forensic dentistry, such as identifying human remains from teeth by matching them to existing dental records; that type of forensic work is generally rock solid and remains unchallenged by critics.  But on identification of perpetrators through bite mark analysis, the question is different: when a forensic “science” has as dismal a record as forensic odontology does, and no scientific proof of its validity exists, can anything justify allowing the use of bite mark evidence to convict a person of a crime?

In NYPD Stop/Frisk Case, US Dept of Justice Recommends Independent Monitor

An update on my May 22  post on the NYPD stop and frisk case: the U.S. Department of Justice has filed a “statement of interest” in the case to say that if the judge rules against the NYPD, the preferred remedy would be an independent monitor to implement changes and make sure they take root.

According to the Wall Street Journal, Mayor Michael Bloomberg reacted by saying that appointing an independent monitor for the NYPD  would be a “terrible idea.”

Independent monitors are common in cases in which the federal government has sued police departments to impose needed reforms to stop patterns or practices of constitutional rights violations in those departments.  For example, police departments in Seattle, Detroit, and East Haven, Connecticut currently have federal monitors; federal monitors have been used in now-completed cases in Los Angeles, Cincinnati, Pittsburgh, and other cities.   Samuel Walker, professor emeritus at the University of Nebraska, explained in the Wall Street Journal article that “monitoring the department would entail a team of people who would conduct audits of reports officers must file for every stop…The team would follow up by interviewing officers and their supervisors about the stops and filing reports to the judge.”

The DOJ Statement of Interest is not binding on the judge; in fact, the DOJ is not a party in the lawsuit.  It was simply used by the DOJ to say that IF the judge found the NYPD to have violated the Constitution (she has made no finding yet), the proper remedy for the violation should include an independent monitor.

Eighty-four Percent of Police Depts. Have No Policies for Proper Eyewitness Identification: NIJ

It has been almost fifteen years since the National Institute of Justice (NIJ) recommended comprehensive changes to the ways that police conduct identification procedures for witnesses.  Yet USA Today reports that a new NIJ report reveals that 84 percent of U.S. police departments still have no policy to govern how live lineups are conducted.

Readers of Failed Evidence know that almost three quarters of wrongful convictions  overturned through DNA feature incorrect eyewitness identifications; it’s the single largest source of error in these cases.  Readers also know that a growing number of jurisdictions (for example here and here,) have adopted changes to eyewitness identification procedures to eliminate these errors, through blind administration of lineups, use of sequential lineups, and other procedures that decades of research has proven to reduce these errors greatly.

But the NIJ study concludes that most of agencies have no policies for how officers conduct these crucial procedures.  Eighty-four percent of the responding police departments said that they had no policy for live lineups, and sixty-four percent said they had no policy for conducting photo lineups.

The study was conducted for NIJ by the Police Executives Research Forum, “a police research organization and a provider of management services, technical assistance, and executive-level education to support law enforcement agencies.”   PERF surveyed hundreds of U.S. police agencies, large and small, to determine how many had at least taken the step of creating a policy to require officers to use at least some of the recognized best practices for eyewitness identification.  PERF researchers found larger police agencies more likely than smaller ones to have a policy in place, but even among the large agencies, fully twenty-five percent did not have a policy.

For those who follow these issues, as I do, the fact that so much of the law enforcement establishment has failed to make changes in basic investigative procedures is not entirely shocking; the resistance to science and the changes it points to is the central theme of my book Failed Evidence.  But the results of the study are nonetheless disappointing, if only because eyewitness identification reform is one of the areas in which there is the greatest consensus that basic changes are needed; there is also broad consensus one what those changes needed most are: blind lineups, sequential lineups, valid ways of dealing with witness confidence statements, instructions to witnesses, and the like.

The Upcoming Travon Martin Trial: How Do Stand Your Ground Laws Work?

Last week, a judge in Florida ruled that the trial of George Zimmerman in the death of 17-year-old Travon Martin will begin next week, as scheduled.  The case will put Florida’s “stand your ground” (SYG) law front and center.  How does Florida’s SYG law work?  What was it supposed to do, and does it accomplish those goals?

I was interviewed on SYG laws on WESA Public Radio’s Essential Pittsburgh on June 3.  (The interview is here.)  Here’s a brief rundown of what I know.

For centuries, Anglo-American law on homicide and self-defense have had a singular goal: avoid violence and death.   If a person is faced with an illegal forcible attack, he or she can engage in self-defense, using as much force as necessary but no more.  An attack with fists can be met with fists, but not with firearms. (Possible exception: the fists of a trained fighter or martial arts expert.)  If one is faced with deadly force, one can use deadly force in self-defense, but if there is a way that one can retreat from the threat  in absolute safety — that is, if the victim can get away without putting himself at risk — the law required him to retreat and avoid the fight.  This was consistent with the overall idea: avoid injury and death if at all possible.

The one exception to the rule of safe retreat was that one did not have to retreat within one’s own home.  This was called the Castle Doctrine: your home is your castle, your ultimate place of safety, and one should not have to flee to safety when they are already at home.

Florida’s SYG law changed this.  A person under deadly attack did not have to retreat in his home, or in any other place that he had a right to be.  There was no more obligation to retreat outside the home; rather, the person could stand his ground and resort to deadly violence in his own defense, even if there was a safe way out of the situation.  In addition, the Florida SYG law put in place strong presumptions preventing a victim who killed an attacker from being criminally charged, and preventing him from being sued.  Most SYG laws have some or all of these features.

SYG laws were supposed to do three things.  First, advocates said the laws would lower the rate of serious crime, because criminals would be deterred.  Second, SYG laws would be a particular deterrent against homicides.  Third, they would put an end to criminal charges against people engaged in legitimate self-defense and the lawsuits that these people were facing from the criminals who they shot (or their survivors).

How has this worked out?

I am a member of the American Bar Association’s National Task Force on Stand Your Ground Laws, which is currently holding a series of hearings on SYG laws around the U.S., and collecting the relevant research studies on these laws and how they work in practice.  (The next hearing is in Philadelphia on Thursday, June 6, and is open to the public; complete information is here.)   The studies show something different than advocates for these laws expected.  The leading scholarship on SYG laws, from researchers at Texas A & M University, shows that in states that have passed SYG laws, serious crime is unchanged — not down — and homicide has shown an overall increase of 8 percent.  (Here is another study that also shows how homicide increases.)  And as far as criminal charges and/or lawsuits, those seem not to have been anything more than anecdotes in the first place.

I’ll post more on what we learn as the Task Force does its work.

New York’s Stop and Frisk Case: With Trial Over, What Should We Expect?

On Monday, May 20, Judge Shira Scheindlin of New York heard final arguments in a trial about stops and frisks by the New York Police Department (NYPD).  The Center for Constitutional Rights and a number of individuals has sued the NYPD.  They allege that the NYPD has used stops and frisks for the last ten years in violation of 1) the Fourth Amendment right against unreasonable searches and seizures,  and 2) the Fourteenth Amendment right to equal protection of the laws, because stops and frisks have overwhelmingly targeted racial minorities — chiefly black and Latino men.   The judge’s decision may not  come for some months.  I discussed the case on NPR’s Tell Me More on May 21 (here) along with Delores Jones-Brown of John Jay College of Criminal Justice.

Here’s a short course on stop and frisk in American law, codified by the U.S. Supreme Court’s case of Terry v. Ohio (1968).  Generally, an arrest or a search requires that police have probable cause to believe that the suspect is involved in a crime.  Probable cause is less evidence than “proof beyond a reasonable doubt,” and less evidence than “more probable than not” (the usual 50.1% of evidence required to win a civil case in the U.S.).  A stop and frisk is less intrusive than a traditional arrest or search: it is a temporary detention (stop) and a pat down of the outer clothing for weapons (frisk).  So it requires only reasonable, fact-based suspicion — an amount of evidence less than probable cause.  To use the Supreme Court’s terminology, an officer may perform a stop when he/she has reasonable suspicion that crime is afoot and that the suspect is or was involved; the officer may also perform a frisk when he/she has reasonable suspicion that the suspect is armed.  Reasonable suspicion is a very low standard of evidence, but it is enough for stop and frisk because the stop is supposed to be brief and temporary, and the frisk is cursory and only for weapons, not a general search for evidence.

In 2002, the NYPD’s own statistics showed that officers performed 97,000 stops and frisks; by 2011, the number had increased to about 700,000.  (You can access the NYPD’s  statistics here.) Crime was already at historic lows in 2002 and is even lower now.  The NYPD claims that the continued drop in crime shows the effectiveness of its intensive use of stops and frisks, even though only about ten percent of these actions yielded any contraband or resulted in an arrest.  Over the same period, roughly 88 percent of those stopped and frisked were black and Latino men, leading to charges that the NYPD stop and frisk program was a form of racial profiling.

Judge Scheindlin’s comments during the final arguments on May 20 lead me to think that she will decide that the stop and frisk activity of the NYPD violates the Fourth Amendment requirement of reasonable suspicion.  She said she thought that getting results in only about ten percent of the cases — and finding guns (the objective of the NYPD’s stop and frisk activity) in far fewer cases than that — showed that the police were acting without even enough evidence to meet the very low standard of reasonable suspicion.  “A lot of people are being frisked or searched on suspicion of having a gun and nobody has a gun…[T]he suspicion turns out to be wrong in most of the cases.”  Proving that the racial skew in the statistics is racial profiling is more difficult, requiring both convincing statistical evidence and evidence of actions by the NYPD that target racial or ethnic minorities.

What do you think?   I’ll be keeping you posted.

Picking a New Police Chief: Design the Process a New Mayor Should Follow

How would you set up the the process to pick a new chief of police for a mid-sized city?

Amidst a corruption scandal, Pittsburgh’s police chief resigned this Spring.  (He has announced he’ll plead guilty to the charges against him.)  This happened with an election for mayor already underway; a short time later, the heavily-favored incumbent dropped out of the race and announced that he would leave the choice of a new chief to his successor.  In a post on March 6 (here), I spelled out what my criteria would be for a picking a new chief.  These included unquestioned integrity, experience as a chief or deputy chief in a police department not less than half the size of Pittsburgh, and a commitment to diversity of all kinds in the ranks.  I said that no excellent candidate, whether an insider or an outsider, should be ignored, and that the process of selection the new chief would be critical, given the circumstances of the chief’s resignation.

Imagine that you have the ear of the new mayor-to-be.  (Which candidate this is will be largely determined in the Democratic Party primary, one week from today; whoever wins the primary is overwhelmingly likely to win the general election in November.) What would be your advice on how the process of selecting the new chief should work?  I can think of a number of possibilities, including:

1) Put together a small group of experts — present and former chiefs of police, law enforcement experts, etc. — to give private, candid advice to the mayor-to-be, regarding what to look for in a successful chief.

2) Create a citizens advisory board to advise the mayor on this important choice.

3) Hold a town hall meeting or two to gather a large and wide swath of public comments on the choice.

4) Conduct focus groups, each with members drawn from all of the important stakeholder groups: citizens, rank and file officers, police union officials, the faith community, the business community, neighborhood advocates, etc., to ascertain what kind of person, with what kind of qualities, the mayor should look for.

What are your ideas?  Have you been through this process before, in any role?  I would very much like to hear from anyone and everyone with thoughts on this.  The choice is coming for Pittsburgh, and it’s going to be crucial.

Thanks for your help.

Brooklyn DA’s Probe of 50 Convictions Featuring One Detective: Conviction Integrity Unit, False Confessions in the Spotlight

With the news that the District Attorney of Brooklyn is re-examining convictions in 50 cases featuring the work of one particular detective (see stories here and here ), we see two issues that have surfaced on the Failed Evidence blog before: false convictions and Conviction Integrity Units (CIUs).

First, the cases under re-examination all involve retired NYPD Detective Louis Scarcella, who had a penchant for getting confessions out of suspects when other detectives could not. According to Scarcella, “there were cases where suspects talked to one detective and they got nothing, and they called me and I got statements. A lot of guys don’t know how to talk to people.”   Some of these suspects who allegedly confessed said that they had told Scarcella nothing.  Scarcella also relied regularly on testimony from one particular drug-addicted prostitute; among the many times she served as Scarcella’s “go-to witness,” she gave crucial eyewitness testimony in two separate murder cases against the same man.  According to one prosecutor who had the woman testify in two trials, “It was near folly to even think that anyone would believe [her] about anything, let alone the fact that she witnessed the same guy kill two different people.”

But there is also this: the re-examinations are being handled by the Brooklyn DA’s Conviction Integrity Unit (CIU), which I wrote about in connection with the exoneration and release of David Ranta, here.  As readers of the Failed Evidence blog know, CIUs are  dedicated units within prosecutors’ offices, just like  homicide or fraud units, that take on the task of re-opening old convictions now in doubt.  The first CIUs were established by DA Craig Watkins in Dallas and former DA Pat Lykos in Houston, and they have begun to pop up in other places.  In New York, both the Brooklyn DA and the Manhattan DA have established CIUs.

The CIU model for examining possible wrongful convictions isn’t perfect; a CIU is, by its nature, not independent of the DA’s office, and could be stopped in its tracks or dismantled completely just as easily as it could be created.  But as I’ve argued here before, they at least represent a step toward accountability for wrongful convictions, in a field in which too few elected prosecutors will touch prior convictions at all.  We should pay careful attention to how this large-scale investigation by the Brooklyn DA’s CIU works out; it will say a lot about whether CIUs can be part of the solution going forward.