Some Caveats Concerning DNA as Criminal Identification Evidence: With Thanks to the Reverend Bayes

The conference panel at which this paper was originally presented was structured along the lines of a debate. The three speakers who were supposed to advocate the use of DNA evidence were labeled, as is customary, Proponents. But those who were supposed to take the negative side were not called Opponents. Rather they were labeled Caveators. I do not know who is responsible for this label, but I think it gets things exactly right. To my mind anyone considering DNA as criminal identification evidence should be a Caveator. The promise and utility of DNA analysis in identifying the perpetrators of such serious crimes as rape and homicide must be acknowledged, but one must also be aware of the limits of the DNA identification process as it now exists and the ways in which these limits affect what experts can reliably tell judges and jurors. In particular, I shall argue below that current practices may lead to misleading claims for reasons that to date have not been fully appreciated by the forensic science community. In making some of these arguments I shall use the Bayesian perspective which Finkelstein and Fairley long ago posited as a paradigm for thinking about identification evidenc

Narrative Relevance, Imagined Juries, and a Supreme Court Inspired Agenda for Jury Research

This paper has its roots in Old Chief v. United States, a case the Supreme Court of the United States decided in 1997. I will begin by describing this case; then comment on its implications for the Supreme Court’s conception of the jury, and conclude by examining the agenda one may draw from it for empirical jury research. Old Chief arose when Johnny Lynn Old Chief was charged not only with assault with a dangerous weapon and using a firearm in the commission of a crime of violence, but also with violating a law that forbids convicted felons from possessing firearms. To prove the “felon in possession” charge, the government sought to introduce a record of Old Chief’s prior felony conviction which disclosed that he had been sentenced to five years imprisonment for an unlawful assault that had resulted in serious bodily injury. Old Chief’s defense was that he never possessed a gun, and he offered to stipulate to the fact that he was a convicted felon and so would have violated the felon in possession law if the jury found he had possessed a gun

A Right to Every Woman\u27s Evidence

I am indeed honored to be here with you today, honored to be joining you next year as Iowa\u27s first Mason Ladd Visiting Distinguished Professor of Law, and honored to be giving the first Mason Ladd Lecture. The honor lies not just in the recognition you accord me, but also in the linkage to the man in whose name this recognition is given

The Honest Scientist\u27s Guide to DNA Evidence

The honest scientist recognizes that she herself is a test instrument, and a fallible one at that. Subjectivity inescapably enters into any human endeavor, and should not be denied. DNA testing is rife with subjective elements, no place more so than at the crucial stage of deciding whether a match exists. On the one hand, non-matching extraneous bands may sometimes be properly disregarded and patterns that do not quite meet objective matching criteria may be appropriately regarded as incriminatory matches. On the other hand, band patterns that do meet objective matching criteria may be treated as exonerative depending on how they deviate from perfect matches. The DNA expert should not hide behind the cloak of science to deny the role of human judgement. White coats should not be worn into the courtroom either literally or figuratively. At the same time, the honest scientist tries to be as objective as possible in her judgements. She realizes that this is inconsistent with a strong a priori belief that the donor of a suspect sample is guilty. Thus she avoids any information suggesting the involvement or uninvolvement of the accused until after she has prepared her report and, in the ideal case, until after she has testified. Laboratories should cooperate to make this easy. Crime-related information should be stripped from all information sent to the analyst unless it is essential to the test and its interpretation (e.g. information that severn people are suspected of participating in a rape or that the suspected rapist is the victim\u27s brother)

Comment: Theory and Practice in DNA Fingerprinting

Throughout her useful paper on DNA identification, Professor Roeder properly attends to both theory and practice. Thus she acknowledges the theoretical soundness of certain criticisms that have been made of the standard paradigm used to evaluate DNA random match probabilities but argues that in practice these criticisms matter little. I am thinking here of the arguments that those cautioning against overweighing DNA evidence have made regarding the undeniable existence of population substructure and its potential implications for independence assumptions supporting the application of the product rule and for the use of convenience samples, such as data garnered from no more than a few local blood banks, to generate estimated allele frequencies for all Caucasians or African-Americans or Mexican-Americans living in the United States. Like Professor Roeder, I believe that these theoretically sound objections have, to date, been shown to be relatively unimportant in practice

Of Flutes, Oboes and the As If World of Evidence Law

Reading Allen\u27s article, I am reminded of a cold war parable I heard during the 1960s. It concerned a flute and an oboe who joined an orchestra one year and immediately set to quarrelling. The flute was distressed because whenever it was playing at its lyrical best the oboe would enter. drowning it out. The oboe was affronted because its deepest, most sonorous passages were invariably ruined by the high-pitched flute butting in. When the orchestra split up for the summer and these quarrelsome instruments went their separate ways, the flute, as it angrily contemplated the oboe, found itself stretching on tiptoes and trying to speak in its lowest voice. The oboe, on the other hand, despite its annoyance with the flute, could not resist speaking in falsetto and hunching over as it played. When the orchestra reassembled in the fall. it had two new clarinets

Desert and Deterrence: An Evaluation of the Moral Bases for Capital Punishment

Because the death penalty was so influential in its development, the law of homicide cannot be thoroughly understood without considering the subject of capital punishment. The question of whether or not the State is justified in taking an offender\u27s life has for centuries been fraught with controversy. Moreover, the law on the subject has become enormously complicated as the courts have attempted to assure that the death penalty is fairly administered

Error BehInd the Plate and in the Law

Casey Stengel, the great manager of the New York Yankees, and later the New York Mets, once dreamed, or so he said, that he had died and gone to heaven. The Lord greeted him personally as he walked through the Pearly Gates. Casey, he said, I\u27m so glad you\u27re here. I want you to form a baseball team. Casey looked around him. He saw Babe Ruth, Lou Gehrig, Ty Cobb, Tris Speaker, Christy Mathewson, Walter Johnson, Grover Cleveland Alexander, and others-all of baseball\u27s immortals-and he said, I\u27ll see what I can do. Obviously, one can do a lot with such talent, and, Casey soon had a team of all-stars at the peak of their talents. The only question was who they could play

Experts, Stories, and Information

In the infancy of the jury trial, there were no witnesses. The jury was self-informing. Members of the jury were drawn from the community. It was expected that they would know, either firsthand or on the basis of what they had heard, the true facts of any disputed incident, and they were gathered together to say what those facts were. Ronald Allen and Joseph Miller, in their insightful paper, see the ideal of the self-informing jury as very much alive today. Allen and Miller tell us that jurors ideally should experience firsthand the factual information needed to arrive at rational verdicts. In their ideal world, jurors compelled to rely on others\u27 accounts would enter the heads of witnesses to distinguish what was actually observed from what was added, lost, or distorted in the recounting process. According to this model, witnesses should educate jurors on relevant facts within their knowledge, and jurors should assimilate the facts presented by the various witnesses to determine both what happened and the implications of those events given the applicable law

After the DNA Wars: Skirmishing with NRC II

This article traces some of the controversies surrounding DNA evidence and argues that although many have been laid to rest by scientific developments confirmed in the National Research Council\u27s second DNA report, there remain several problems which are likely to lead to continued questioning of standard ways prosecutors present DNA evidence. Although much about the report is to be commended, it falls short in several ways, the most important of which is in its support for presenting random match probabilities independent of plausible error rates. The article argues that although one can sympathize with the NRC committee\u27s decision as an effort to say no more than what science reliably tells us, it is not a good forensic science recommendation because following it means that the probative value of DNA evidence is likely to be substantially overstated. Fortunately, it will be the rare case where this matters