Advances in Forensic Science: Legal and Ethical Responsibilities

Presented by Dr. Henry C. Lee at the Montreal Conference, July 1999.

Dr. Henry C. Lee as a young boy fled Mainland China from the advancing communist army to Taiwan where in the mid 1950’s he served as a police supervisor. After arriving in the United States, he worked his way through college and graduate school and received a Ph.D. in biochemistry. Dr. Lee now serves as Commissioner of the Connecticut Department of Public Safety. He is a foremost forensics expert having personally worked homicide trials around the world as well as high profile cases in the United States.

Introduction

Forensic science is the application of the natural sciences to matters of the law; it includes a variety of different activities and specialties. In practice, forensic science draws upon the principals and methods of all the traditional sciences, such as physics, chemistry, biology and mathematics. The term forensic science is sometimes used as a synonym for criminalistics. Both terms encompass a diverse range of activities. Forensic science is also defined in a broader sense to include forensic medicine, odontology, forensic anthropology, forensic psychiatry, forensic toxicology, forensic radiology, forensic entomology, forensic climatology, forensic engineering and criminalistic.

The major specialty areas included in the wider definition of forensic science are described briefly below. Forensic medicine is the application of medicine and medical science to legal problems. Its major concern is the cause and circumstances in cases of questioned death. Forensic odontology is the application of dentistry to human identification problems. Forensic odontologists are concerned with the identification of persons based upon their dentition, usually in cases of otherwise unrecognizable bodies or in mass disasters. They also analyze and compare bitemark evidence in many types of cases. Forensic anthropology has to do with personal identification based on skeletal remains. Other areas of forensic anthropology include establishing databases on bodily structures as functions of sex, age, race, stature, and so forth. Forensic toxicology has to do with the determination of toxic substances in human tissues and organs. Much of toxicology concerns the role toxic agents may have played in Causing or contributing to the death of a person. Forensic radiology is the application of radiology to the identification of injury and unknown substances such as bullet, bomb and other objects. Forensic psychology has to do with the evaluation of psychiatric conditions of an individual and his action related to crime. Criminal profiles and psycholinguistics are other areas related to forensic psychology. Forensic entomology is the study of insects and larvae in criminal investigations. Forensic climatology is the application of the knowledge in weather conditions to determine the factors related to body changes after death. Forensic engineering has to do with the determination and reconstruction of material failures involving accidents, disasters and fires. Criminalistics includes the areas such as fingerprint comparison, question documents examination, firearms and toolmarks comparison, drug identification, comparison of imprints and pattern evidence, identification of accelerant and explosive residues, examination of blood and body fluids, identification of hair, fiber, glass, soil and other types of trace and transfer evidence. It is the broadest of the subdivisions of forensic science.

Concepts in forensic examination

The dimensions of a forensic science investigation may include any or all five major activities in analyzing and interpreting physical evidence: (1) recognition, (2) identification, (3) comparison, (4) individualization, and (5) reconstruction.

Recognition

Recognition is the ability to separate important and potentially informative items in a case from all the background and other unrelated materials. The evidence is selected based on what is likely to help in distinguishing between the possibilities. The recognition process involves basic principles of forensic examination; pattern recognition; physical property observation; sometimes field testing; and information analysis. Recognition is probably the most important step in the analysis of forensic evidence. Without it, no amount of further laboratory examination of scientific analysis is likely to shed much light on the case. If crucial evidence is not recognized and properly collected and preserved, it will be lost, and any important links between a suspect and the crime that it may have been able to provide will never be known or established.

Identification

Identification is a process common to all the sciences and, in fact, to everyday life. It may be regarded as a classification scheme, in which items are assigned to categories containing like items, and given names. Different items within a given category all have the same generic name. In this way, botanists will identify plants by categorizing them and naming them. Likewise, chemists identify chemical compounds. In forensic science, identification usually means the identification of items of physical evidence. Some types of physical evidence require that scientific tests be conducted to identify them. Drugs, arson accelerants, bloodstains, and seminal stains are examples. Objects are identified by comparing their class characteristics with those of known standards or previously established criteria.

The procedures used for identification generally include one or more of the following types of examinations:

1. Physical measurements
2. Physical properties
3. Chemical properties
4. Morphological properties
5. Biological properties
6. Immunological properties

In many case identification is the beginning of much more complicated forensic analysis. On the other hand, identification may sometimes be all that is required, as in the case of narcotic or drug identification, manner and cause of death determination, identification of type of bone remain, determination of weapon type, shoe print size determination, or identifying the nature of a biological sample.

Classification

Classification is done by comparing the class characteristics of the questioned evidence with those of known standards or control materials. If all the measurable class characteristics are the same between the questioned sample and the known control, then these two samples could have come from the same source or origin. If there are significant differences in some of the class characteristic measurements, then the questioned sample can be absolutely excluded as coming from the particular source. In other words, the exclusionary value of comparison in the forensic field is considered absolute. Depending on the nature and type of the physical evidence, no further analysis can be made beyond the comparison step with many types of physical evidence due to inherent limitations. The following are some methods used to compare physical evidence:

a) Chromatographic methods, e.g. paper, TLC, column, GC, HPLC, electrophoresis, etc.

b) Spectroscopic methods, e.g. emission spectrography, AA, plasma emission, UV-VIS, JR. and FTIR.

c) Composition analysis, e.g. AA, plasma emission, NAA, Mass. spec, SEM-EDAX and x-ray diffraction.

d) Microscopical examination, e.g. stereoscope, compound microscope, phase contrast, comparison microscope, SEM, and IR and UV microscope.

e) Biological, e.g. enzyme assay, electrophoresis, serological typing, and DNA analysis.

Individualization

Individualization is unique to forensic science; it refers to the demonstration that a particular sample is unique, even among members of the same class. It may also refer to the demonstration that a questioned piece of physical evidence and a similar known sample have a common origin. Thus, in addition to class characteristics, objects and materials possess individual characteristics that can be used to distinguish members of the same class. The nature of these individual characteristics varies from one type of evidence to another, but forensic scientists try to take advantage of them in efforts to individualize a piece of physical evidence can be truly individualized, but with some other types an approach to the goal of individualization is possible. We refer to these as partial individualization, and in some cases they are nothing more than refined identifications, such as genetic marker determination of a bloodstain, DNA typing of semen evidence, or trace elemental analysis of paint chips. The term identification is sometimes used to mean personal identification (the individualization of persons). Fingerprints, for example, can be used to identify an individual. The technology is unfortunate, since this process is really an individualization. Likewise, dental evidence and dental records may be used by a forensic odontologist in making personal individualization in situations where dead bodies cannot be readily identified otherwise (such as in mass disaster, or in cases of fire or explosions).

Reconstruction

Reconstruction is based on the results of crime scene examination, laboratory analysis, and other independent sources of information to reconstruct case events. Reconstruction often involves the use of inductive and deductive logic, statistical data, information from the crime scene, pattern analysis, and laboratory analysis results on a variety of physical evidence. Reconstruction can be a very complex task, linking many types of physical evidence, stain pattern information, analytic results, investigative information, and other documentary and testimonial evidence into a complete entity.

The developing fields of artificial intelligence and expert systems have opened up a new dimension in reconstruction. These systems allow forensic scientist modeling and representation of laboratory analysis results, reasoning and enacting of a crime scene, logic, comparing and profiling of a suspect, and making logic decisions concerning the case. Advances in hardware and software have added systematic problem solving to forensic scientist’s repertoire. Computer technology allows communication between the user and the expert system—in a sense each is helping the other to solve a specific forensic problem. Reconstructions are often desirable in criminal cases in which eyewitness evidence is absent or unreliable. They are important in many other types of cases too, such as automobile and airplane accidents, fire and arson investigations, and major disasters.

Forensic Science in the legal system

Forensic science, by its very nature, has to do with legal matters and legal questions. One of its main characteristics, therefore, is its interaction with the elements of the justice system. Many disciplines in forensic science are concerned almost exclusively with criminal cases, and they deal almost entirely with the criminal justice system. There are many kinds of civil cases, however, in which physical evidence and forensic science have important roles.

Civil cases usually involve disputes between individuals or organizations and they can encompass a variety of situations in which physical evidence can play an important role. Examples include, questions concerning the authenticity of a last will and testament; cases involving mechanical or materials failure of a product; cases involving persons who have suffered bodily harm or death as the apparent result of mechanical defects or failures; and cases involving in matrimonial disputes or contested divorce.

Forensic science comes to public attention most often as a result of involvement in major criminal cases. From a scientific point of view, the distinction between civil and criminal is artificial—the distinction is a legal one. In any type of case, the principles and procedures of the forensic science investigation remain the same. Recognition of physical evidence, its proper preservation, and analysis can often provide important information to courts and to juries in helping them resolve the scientific issues.

Legal and ethical responsibilities of forensic science laboratory services

Science deals with natural phenomena, while law deals with man made rules and regulations. As we know, forensic science is the application of scientific principles and techniques to matters of law. Because of its unique application, a forensic scientist must not only master the scientific methods but also must know the limitations of science. A forensic scientist not only has to be familiar with the law but also has to appreciate the rules of evidence. As scientists, we have to possess the ability to observe the skill of documentation, the knowledge of examination, and the power of reconstruction. On the other hand, we also have to follow procedures, obey the rules of evidence, maintain impartiality and stay within the legal scientific boundaries. This is often more easily said than to practice. Too often, we forget that we are supposed to be the neutral party. We have to report whatever we observe, whatever we find, no matter what we believe. However, oftentimes, we tend to report, whatever we want to see, whatever position we want to find, and whatever theory favors our case.

Fifty years ago, this was the practice in our profession and no one ever questioned the merits of this type of practice. The sole usage of physical evidence was to link a suspect to a crime and to prove someone’s guilt. During that era, the forensic laboratory was commonly referred to as the police lab or the crime lab. The laboratory was seen as just an arm of the police and the function of the lab was to solve crimes. With time came the Civil Rights Movement, we moved from Kennedy’s idealism to Nixon and Watergate. Through the efforts of many forensic scientists such as Paul Kirk and Milt Halpern, there was a revolutionary change in the concept of forensic services. Physical evidence is no longer just used to link a suspect to a crime but it is of equal importance in exonerating a person of guilt. The exculpatory evidence is equally emphasized as the inculpatory evidence. The laboratory is no longer just for the prosecution; the defense should have equal access to such services. Today, the laboratory is more correctly referred to as a forensic science laboratory and no longer just a crime lab or a police lab. During this transition, many good things happened in the forensic field. The AAFS, ASCLD, IAI, all the regional associations, and other forensic professional organizations have played an important role in leading this transition. Most of the forensic scientists and forensic laboratories in the world have taken the opportunity, have gotten on board the train, and now enjoy the fruits of this change. However, there are still few left on the platform, watching as the train passes away without them. These few have created a new set of problems for our profession. In the early days, we used to get-away by simply telling the court to "trust me," this is our result and don’t question our findings. In general most of the lawyers accepted our reports as are. Laboratories never needed to rely on standards, notes, or proficiency tests. The forensic scientist did not need quality control or quality assurance programs. This was until we heard the following errant testimony: A serologist said that type A blood when mixed with type B blood yielded Type 0 blood. A hair examiner identified a hair as being of Puerto Rican origin, or that it matched a questioned hair with post mortem banding to a known hair sample from a live suspect. A dentist identified an abrasion mark as a bite mark and was able to match it to the suspect’s teeth. A corner identified a dead rabbit as a baby.

Now, we are again at a crossroad, the whole forensic field is once again under the looking glass. Are we really as impartial as we are supposed to be? Are we truly non-biased? Do we really have an open mind when we conduct our examinations? Are we really treating the prosecution and defense equally? Are we really independent from police and prosecution influences? Are we really able to produce the high quality as we claim? Are we really confident in the product we produce? Once again, our professional organizations, AAFS, ASCLD, ASCLD LAb, ABC, LAJ, AFT, NLJ, and other associations have looked into the future and have undertaken the challenge to develop accreditation programs, proficiency testing projects, and certification projects

Most forensic science laboratories in the United States are publicly operated, and may be part of federal, state, county, or local government. Many laboratories are housed within police or federal law enforcement agencies. Laboratories, which operate under police departments or prosecutors’ offices, are generally not available to the defense. The situation is a reflection of the adversarial nature of the justice system and is in part, a reflection of the way in which organized laboratory services have evolved. The adversarial relationship between the state and the defendant tends to place the forensic experts engaged by one side or the other into an adversary relationship as well. Most forensic scientists, regardless of who employs them or engages their services, think of their results as entirely objective and try not to allow themselves to be forced into adversarial roles.

Many people have thought about the problems associated with fairness in providing forensic services to the prosecution as well as to the defense. A great deal has been written on the subject, and a variety of solutions has been proposed. Forensic scientists are inclined toward the view that their function is to employ scientific procedures to unearth factual information about the physical evidence in a case. For the vast majority areas of forensic science, this task is one which will yield an objective set of results which is in no way altered by the fact that one side or the other engaged their services or intends to call them as witnesses. Most forensic scientists think of themselves as unprejudiced and make every effort to ensure that their work is objective. They think of their results as a way of providing information to the court, rather than to one side or the other.

Although the majority of forensic scientists put forth every effort to maintain objectivity, there is no doubt that different ones can disagree about the meaning or interpretation of results.

Perhaps the most important issue in the forensic science field is to establish a professional standard. An assessment is needed of standards of practice in the collection, examination, and analysis of physical evidence. Both forensic and legal professions must carefully examine their role in examining and presenting scientific evidence in the court of law. The professionalism and ethical standards of both groups in criminal and civil litigations should be developed.

Conclusion

Forensic science has emerged as a significant element in efforts to resolve civil and criminal matters in our society. The value of forensic evidence has been demonstrated in all aspects of civil and criminal investigations. In recent years, the court has become increasingly dependent on forensic evidence in civil and criminal litigations. As science and technology continue to advance, the importance and the value of forensic science in the protection of our society will also continue to grow.