Scientific Method Applied to Forensic Science

The procedure by which scientists, communally and over periods, attempt to assemble a precise interpretation of the world, is referred to as the scientific method.  The desired result is that of an unswerving, non-capricious and consistent portrayal.  Perceptions and interpretations of natural phenomena can be influenced by personal and cultural beliefs; however, the application of criteria and standard procedures assists in the minimization of these archetypal persuasions while developing a theory.  The scientific method attempts to reduce the presence of prejudice or bias in the assessor when examining theories and hypotheses.

The scientific method is comprised of four steps:

“1) observation and description of a phenomenon or group of phenomena; 2)  formulation of a hypothesis (or hypotheses) to explain the phenomena; 3)  use of the hypothesis to predict the existence of other phenomena, or to predict quantitatively the results of new observations; and

4) performance of experimental tests of the predictions by several independent experimenters.”  (Wolfs, 2007, ¶3.)

According to Wolfs, a popular statement is “in science that theories can never be proved, only disproved.  There is always the possibility that a new observation or a new experiment will conflict with a long-standing theory.”  (Wolfs, 2007, ¶4.)  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.  High stakes are riding on the outcome for both parties involved:  defense counsel desires an acquittal as it builds on their reputation in the legal community and prosecutorial counsel desires a conviction as it builds on their reputation in the legal community.  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 1988 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.  (Bergman, 2004, ¶2.)

Finally, begrudgingly “after all this time Pope John Paul II finally conceded that the church had made a ‘mistake’. 1988! Over three centuries to concede a scientific point that every man of reason had accepted two hundred years before.”  (Bergman, 2004, ¶3.)  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.

Observation And Description Of A Phenomenon Or A Group Of Phenomena

The first step involved in the scientific method is the observation and description of a phenomenon or a group of phenomena.  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.  Trajectory paths would also be examined to conduct the bullet’s route.  The following paragraph will discuss the usage of the hypothesis to predict the existence of other phenomena or to quantitatively predict new observation results.

Use Of The Hypothesis To Predict The Existence Of Other Phenomena, Or To Predict Quantitatively The Results Of New Observations

The third step involved in the scientific method is the use of the hypothesis to predict the existence of other phenomena, or to predict quantitatively the results of new observations.    The hypothesis is the “tentative answer to the question: a testable explanation for what was observed.”  (Carter, 1996, ¶13.)  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.  This is not to be confused with a generalization, as a generalization is based on inductive reasoning.  The hypothesis is the potential account for the observation.   (Carter, 1996, ¶15.)  Forensic scientists and all scientists in general:

“build on the work of previous researchers, and one important part of any good research is to first do a literature review to find out what previous research has already been done in the field. Science is a process — new things are being discovered and old, long-held theories are modified or replaced with better ones as more data/knowledge is accumulated.” (Carter, 1996, ¶19.)

Science is a continually evolving discipline involving ongoing research.  Oftentimes experts have presented erroneous opinions, which must be challenged.  The following paragraph will discuss the importance of experimental tests conducted by several independent experimenters.

Performance Of Experimental Tests Of The Predictions By Several Independent Experimenters

The fourth and final step involved in the scientific method is the performance of experimental tests of the predictions by several independent experimenters.  This aspect actually denotes whether or not the hypothesis is supported by the results.  Once the experimentation has been conducted and predicted results achieved, the hypothesis is reflected to be plausible.  The experiment must be a controlled experiment performed by several independent experimenters.  The forensic examiners, scientists must “contrast an ‘experimental group’ with a ‘control group.’” (Carter, 1996, 15.)  The replication aspect, several experiments, is critical.  The experimentation should be attempted various times on various subjects.  This is imperative to determine that a result is not simply coincidental, rather intended and certain.

Forensics science is critical in the application to law and legal questions as justice is hinging on steadfast and accurate results.  Fortunately, science and technology have vastly improved in recent years to reduce the number of erroneous indictments and convictions for the innocent.  Likewise, this discipline is reaching perfection in that an offender or culprit is almost certain to be apprehended given the likelihood that minute strands of trace evidence is almost always located at the scene of a crime.

Striving for excellence is oftentimes accompanied by adversity, as in Galileo’s stance; according to Bergman, “the actual threat of Galileo to his contemporary scientists was less his position on heliocentricity than his insistence on observation, research, and experimentation to determine reality. It was for this reason that G. A. Magnini, an eminent astronomy professor at Bologna, openly declared that Galileo’s observations, which indicated that Jupiter had satellites, and must be incorrect. Although the scientific revolution emerged gradually, and many of Galileo’s ideas can be traced to before the thirteenth century, Galileo openly challenged the whole system of determining truth that existed then, and therein lay most of his problems” (Bergman, 2004, ¶20.)


This essay has discussed the four steps of the scientific method in relationship to forensic science, providing examples of how each step is incorporated into the process during a criminal investigation.  The accuracy of the findings of forensic examination is critical in the public’s reliance and the credibility of the criminal justice process.  It is important that evidence is not compromised for these experts to perform their craft with conviction.


Bergman, J. (2004). The Great Galileo Myth. Retrieved February 3, 2008, from A.D.A.M. Web site:

Carter, J. (1996). The Scientific Method. Retrieved February 3, 2008, from University of Cincinnati Web site:

Wolfs, F. (2007).  Appendix E. Introduction to the Scientific Method. Retrieved February 3, 2008, from University of Rochester Web site:


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