Scientific Method Applied to Forensic Science | Justice and Security
It also highlights how the scientific method is at the core of forensic science. The scientific method uses a very specific set of steps, as explained in the video. The types of crime involving forensic science application typically consist of murder, rape, The scientific method is comprised of four steps. Defend each step of the scientific method as necessary to psychological research 3) test the hypothesis, and 4) draw conclusions and refine the hypothesis. theory to psychology took the discipline from a form of philosophy to a form of science. Descriptive studies describe the nature of the relationship between the.
The prosecution and defense in a criminal prosecution will each possess experts attempting to discredit the other. Many times cases have been lost due to technicalities or mishandling of evidence.
Law is a play of words and circumstances, the courtroom a theater in which both sides are playing for keeps.
Scientific Method - The four steps of the scientific method.
High stakes are riding on the outcome for both parties involved: Likewise, forensic expert witnesses generally affiliate with either defense or prosecutorial counsel and are limited to solely testifying on behalf of the side in which a relationship has formed. The reasoning for this policy is simply that their opinions can be misconstrued if it is deemed that the expert possesses a fickle nature or is solely involved for financial compensation in the case.
It is par for the course that in the legal arena, theories will always be challenged, as this is the nature of the beast. Moreover, with disproving of a theory or challenging an authority on issues, there is always the possibility of ramifications. For example, Galileo was only pardoned in by the roman catholic church for disputing the heliocentric solar system position. According to Jerry Bergman, in The Great Galileo Myth, Galileo was actually opposed more so by his scientific colleagues as opposed to religious authorities.
The roman catholic church only became involved after receiving undue pressure from the academia community. Over three centuries to concede a scientific point that every man of reason had accepted two hundred years before.
Therefore, it is not for the faint of heart to question titans in religion or science unaware of the potential ramifications, which may lie ahead.
The following paragraphs will discuss the four individual steps in the scientific method and their application to forensic science in a criminal investigation. The forensic examiner must observe an incident or situation. How this scientific method step relates to forensic science would be, for example, in a crime scene investigation involving ballistics.
The observation would be of a particular bullet impression in an environment. Perhaps the defense in the case would rise in their legal argument that the defendant could not possibly have murdered the victim given the point of entry and point of exit wounds or the type of bullet involved. The forensic examiner on the particular case may have the responsibility of disputing this claim. Forensic ballistic examination in criminal cases is not limited solely to ballistics, rather encompasses bloodstain pattern analysis as well involving projectile.
The following paragraph will discuss the formulation of a hypothesis. Formulation Of A Hypothesis Or Hypotheses To Explain The Phenomena The second step involved in the scientific method is the formulation of a hypothesis or hypotheses to explain the phenomena.
Essentially, this is the framing of a question or theory around the incident. Perhaps there is a particular firearm in question or perhaps the firearm is undetermined at this juncture. The forensic examiner would then determine whether or not the bullet came from a particular gun in question. Tool mark and firearm examinations would be conducted to determine, consisting of analysis of ammunition, tool mark and firearm evidence, to establish whether the weapon in question was employed during the commission of the crime in question.
The following paragraph will discuss the usage of the hypothesis to predict the existence of other phenomena or to quantitatively predict new observation results. The forensic examiner or scientist attempts to explain what has been observed. This cause and effect relationship, the hypothesis is the possible cause, while the observation is the effect. It also recognizes the ability of the forensic expert to reason from events to findings Fig. The forensic examiner, forensic pathologist or other consultant first obtains information about the incident of concern — the crime, the assault, the death, etc.
The examiner anticipates the questions that others — family members, public health agencies, insurance agencies, law enforcement officers, attorneys, and the courts — will ask in the future. Then, the examiner performs scientific procedures — an autopsy, the retrieval of evidence from a crime scene, crime scene photography, or any other forensic science analysis such as toxicology or firearms examination — with a focus on finding answers to the anticipated questions.
If the witness accounts do not agree with the physical findings, then the witness or witnesses are not telling the truth.
Understanding The Scientific Method
During the analysis, the examiner may need to obtain more information until the quality and quantity of the information are sufficient to make assessments. Once the assessments are complete, the examiner then can offer opinions but only to a reasonable degree of medical or scientific certainty.
The examiner must always keep in mind the limitations of science when rendering opinions. This method is not new. Many well-trained, American forensic pathologists working in busy coroner and medical examiner offices have employed the same or a similar method to determine cause and manner of death for decades.
Wright and Tate used a flow chart describing this method Fig. Except for some minor differences, this flow chart shares most of the characteristics of the forensic scientific method described in this article.
The Scientific Method.
It emphasizes the need to obtain anamnestic data and to correlate that data with procedural findings. Most importantly, it indicates that the hypothesis is to be generated from the anamnestic data and not the physical evidence.
The standard scientific method does not allow for the acquisition of witness information. Scientists using the scientific method generate hypotheses from the observations of physical evidence only.
Once again, this does not work when dealing with past events. The forensic scientist does not form a hypothesis as a natural or physical scientist would. The scientific method uses falsification, but the forensic scientific method uses both verification and falsification Table 4. The strategy of falsification in the standard scientific method allows for other explanations for experimental results.
It prevents scientists from closing their minds to other possibilities. The forensic scientific method must also use a careful approach in order to prevent an injustice. Allowing the witnesses, particularly the suspect, to shape the hypothesis and then verifying that hypothesis with further testing allows the benefit of the doubt to be with the suspect.
This is because a suspect and most witnesses ideally are not allowed to know the forensic science findings before making statements. Also, most people do not know enough about science to form false statements that will perfectly match the findings.
Armed with information from the crime scene, the crime laboratory and the autopsy suite, an interrogator may question a witness and evaluate the veracity of his or her statements without the witness being aware of the scientific findings or that such findings even exist. A sufficiently trained interrogator with the help of the scientist can easily detect a lie in this setting.
With some crimes, reliable primary witness information might not be available or obtainable. The prosecutor or plaintiff then has to rely on indirect or circumstantial evidence — much of it possibly from forensic science methods — to try a case. Proof in a case like this requires the prosecutor or plaintiff rather than the witnesses to form the hypothesis.
The prosecutor then must reason more from the findings to the events rather than the opposite and must argue that a guilty verdict is correct based on high probability. The strategy used — either by the prosecutor or plaintiff as he or she considers whether or not to file charges or by the defense attorney during the trial — is falsification.
All that is needed to falsify is to demonstrate convincingly how one plausible, alternate scenario can explain the physical evidence. Cases relying on circumstantial evidence have other challenges. Arguments based on probability are subject to certain biases 9. These biases come from the tendency to prove a hypothesis or scenario rather than to falsify it.
Three forms of bias are particularly common. A tendency to select the first alternative that comes to mind consistent with the evidence — a bias known as satisficing — may prevent the analysis of other alternatives. Even when more than one alternative is considered, the limitations of the human mind to form and remember lists may limit the explanations to only those available to the imagination.
The bias of availability limits the number of considered possibilities. Finally, if one scenario is considered and additional evidence shows it to be incorrect, the next scenario that is considered may not differ much from the first one. This is because of anchoring. The truth may not resemble either the first or second scenario at all, but the tendency of the human mind to anchor additional hypotheses to the first one will limit the considered possibilities.
The Limitations of Science: Most in our society have a profound belief in science. Science in the courtroom is afforded greater respect than witness accounts. Those of us who work in the forensic sciences have a view opposite to this juror.
Many of us are acutely aware of the limitations of science, particularly when that science is directed toward the recent past.
Additional information in the form of new witnesses or other physical evidence can alter the interpretation of findings. The awful truth is that science is a human endeavor with definite limitations.
This is not to say that witness accounts do not have limitations because they certainly do. On the other hand, witnesses often provide much better, more detailed and more reliable data than scientists.
History often trumps science, particularly if multiple reliable sources document that history. Consider what happens when witness accounts are sparse or questionable. In these situations, scientists more often cause confusion rather than clarify the issues. Three of the most controversial and misunderstood topics in forensic pathology involve situations where witness accounts are non-existent or highly questioned. One example is the common situation where an infant is found unexpectedly dead after being put to bed.
With SIDS, there are no witnesses to give an account of what happened physiologically to the child. There are no electroencephalograms, telemetry, and measures of respiratory function to explain the death. Scientists do not fill the void left by the absence of a witness account; instead, hypotheses abound. Two other controversial topics, the sudden and unexpected death of a person under police custody or the death of a child from physical abuse, are controversial because the public questions the truthfulness of the eyewitnesses — in many cases, the police or the parents.
As with SIDS, scientists do not always provide clear and conclusive answers. Rather, scores of scientists line up and step forward with varying and diverse opinions. Many would be surprised how often professionally trained scientists disagree with each other. Even technologically powerful DNA analyses are subject to limitation. Although these tests can provide exceedingly high probability ratios, giving the appearance of near certainty, analysts can make mistakes in sampling the evidence, performing the analysis, or applying the results.
The courts should use the forensic sciences to evaluate witness accounts rather than to replace them. The triers of fact in the court setting must understand the limits of science before reaching a verdict.
The Basis for Forensic Science Knowledge: Davis, an American forensic pathologist and a long-time advocate of learning from the death scene, describes the 81, case files in the Miami-Dade County, Florida, Medical Examiner Department as chapters in a textbook for learning forensic pathology and training forensic pathologists Each file, with both anamnestic and anatomic data, contains unique sets of past events. Each provides the basis by which a pathologist learns to reason from the events of the past to the subsequent forensic and anatomic findings.
Each forensic pathologist or forensic scientist — in training or through practice — learns science through experience — both his or her experience and the experiences of others. Each previous case or analysis, if properly understood and interpreted, can contribute to the knowledge that the scientist applies to each new case. Also, knowledge gained from the natural and physical sciences, the experiences of others, and experiments performed in the present can be applied to any forensic science issue, provided that the information is used in the proper way and in the proper context.
As a gatekeeper for the proper application of science to a court case, the court evaluates the experience and training of the analyst before declaring him or her an expert. It is also and perhaps even more appropriate for the court to evaluate the scientific method of the analyst.
- Heartland Forensic Pathology, LLC: Finding the Truth Behind the Death
- The scientific method
Do the opinions of the expert, particularly opinions that involve causation, go beyond a simple focus on the scientific data? Has the expert appropriately used the forensic scientific method, comparing witness and anamnestic data to the physical evidence?
Without the proper method, the experience of the expert is not only useless but also potentially harmful. The courts require a medical or scientific expert to express only opinions made to a reasonable degree of medical or scientific certainty. The courts in the United States have never specifically defined this term, leaving it somewhat to the discretion of the expert In the context of the forensic scientific method, reasonable certainty requires the scientist to reason using appropriate methodology — reasoning logically from hypothetical or real events to findings — and, having done so, to express opinions that he or she is certain are true.
The origin and development of the Shaken Baby Syndrome SBS provides an excellent example of what can happen when scientists and physicians apply the scientific method inappropriately to past events.
To support his hypothesis, he presented 27 cases in his paper and added in a few more cases to the original 27 cases. Each case presentation was scantly detailed, and the witness information came mostly from confessions to a crime.
Some of the cases involved only long bone or vertebral injuries without head injuries. This situation differed markedly from the typical shaking scenario described in later years. From these observations and perhaps other observations that he did not mention, Caffey hypothesized that even innocent, socially acceptable and habitual practices of shaking were leading to permanent brain damage in thousands of children every day in the United States.
He believed even mild shakings over time had doleful consequences to brain function. The entity has had many believers over the years, but there have been some who do not believe that children can be severely injured by shaking Modern forms now included cases where there was evidence of impact. There were also now more male perpetrators than female perpetrators and more rib fractures than long bone fractures. Recently, several have moved away from the use of the SBS term, relying instead on more general terms that include both shaking and blunt head trauma, such as Abusive or Inflicted Head Injury Some have studied the medical literature of SBS.
According to Donohoe, much of the clinical literature prior to consisted of consensus papers or retrospective studies with considerable methodological constraints Leestma found in the literature 54 cases with admissions of shaking by perpetrators, but only 11 cases had no sign of cranial impact. The majority of the cases also had no individual case data Experimental studies performed by or with biomechanical experts also generated controversy and mixed results.
Two biomechanical studies provided data that did not support the concept that brain injury could be caused by shaking alone 22 23but one study indicated that brain injury from shaking alone is possible if the shaking is vigorous Another biomechanical study indicated that shaking severe enough to cause subdural hematomas would cause the cervical spine to fail mechanically Others, however, criticized this study for its design Adding to the confusion, numerous observers in case reports and studies found retinal hemorrhage, an important condition for the diagnosis of SBS, associated with an enlarging number of conditions not related to child abuse Shaken Baby Syndrome and the Scientific Method: Caffey, true to the scientific method, invented a hypothesis to explain a set of physical findings that to him constituted a syndrome.
He did not ask for the detailed accounts of witnesses, and he did not allow the witness accounts to form the hypotheses. Instead, he formed his own hypothesis from physical data, overlooking the fine detail from witness accounts in each case. The standard scientific method cannot and does not work with past events, and it did not work for Caffey.
Although he noted a set of clinical and radiological findings in and later, Caffey never observed the events that caused those findings. No one can observe past phenomena. He could only surmise that shaking was the only possible event in every single case capable of causing the deleterious lesions.
Essentially, he selected one scenario out of the numerous possible scenarios available in widely varying cases. The confessions of the accused did not satisfy the requirement for the detailed eyewitness testimony called for in the forensic scientific method. We have no way of knowing from the case studies presented by Caffey or many others whether or not shaking was mentioned to the accused prior to the confession. Confessions to infant shaking under those circumstances would not be surprising.
Interrogators could easily lead suspects to believe that any event that included any kind of shaking, no matter how trivial, could cause deleterious consequences to the brain, particularly when Caffey and others promoted that belief. A confession in that setting would then be an expression of perceived guilt, regardless of whether or not an episode of shaking, no matter how brief or prolonged, caused any harm.
Suspects could also use the shaking explanation as a way to keep from admitting the infliction of more socially unacceptable forms of head trauma. False confessions are well-known and well-documented phenomena, and numerous different social factors can lead to them during a police interrogation The increase in the number of confessions to shaking with time suggests that police interrogators introduced the idea to suspects more frequently with time.
In spite of the numerous experiments and studies on SBS, scientists and physicians can never determine from these studies the past events of any infant head injury case. Scientists conducting experiments and controlled observations can only use them to predict what could happen under a specific set of circumstances, not what actually happened in the case. In other words, experiments and controlled studies can only determine what is or is not possible, not what actually occurred.
Over the years, experiments, particularly the biomechanical experiments, have added to our understanding of how the head and brain react to trauma. Even though they have added to our knowledge of head injury, not one of these experiments could determine the past events of any case.
Only the forensic scientific method could do that with any reasonable certainty. The forensic scientific method is not for the development of a theory, like what SBS has seemed to become over the years. Proper use of the forensic scientific method would not allow any such concept to be introduced into the analysis.
Forensic scientists would need only an eyewitness account to compare with the findings, preferably one that is not encumbered by added notions or theories. Unfortunately, the proponents of SBS today prefer to rely on shaking; however, unlike what is called for with the standard scientific method, there have been few attempts to falsify that hypothesis. Instead, the proponents have tried to promote and support it.
Consequently, the biases of satisficing, availability and anchoring mentioned earlier in this paper have come into play. Infant shaking remains the first or nearly the first consideration in most pediatric head trauma cases satisficingand there has been little interest or capacity to consider other options availability. Also, even though most of the cases over the years have evidence of cranial impact and even though recent biomechanical studies indicate falsification, many remain anchored to the shaking concept.
Remarkably, even Duhaime and colleagues remained anchored to shaking, even though their biomechanical study did not support the shaking hypothesis.
The final paragraph of their paper made this evident: It is our conclusion that the shaken baby syndrome, at least in its most severe acute form, is not usually caused by shaking alone.
Although shaking may, in fact, be a part of the process, it is more likely that such infants suffer blunt impact. The most common scenario may be a child who is shaken, then thrown into or against a crib or other surface, striking the back of the head and thus undergoing a large, brief deceleration Conclusion — the Need for the Forensic Scientific Method: Science is, or should be, about the truth.
Truth in its abstract, spiritual or metaphysical forms is important, but science deals only with empirical truth. The scientific method has proven itself over time to be a reliable way to arrive at real, measurable, observable truth. Past events, by their nature of being in the past, have passed from real to abstract.