Psychology differs from other sciences, such as physics or chemistry, where test conditions and parameters are easier to control. In psychology, there are factors that are easily controlled, but there are also circumstances that are beyond the control of the researcher. For instance, the researcher cannot control a history of abuse, or social teaching that occurred in the subject's childhood. All of these factors could affect the outcome of the test, but are not controllable from the researcher's standpoint.
The presence of confounding variables makes it difficult to attribute the study findings to the hypothesis beyond the shadow of a doubt. Confounding variables, such as we have discussed, make it difficult to isolate the independent and dependent variable. This is another key criterion of a valid empirical study. In order to demonstrate causality, the researcher must be able to isolate the independent and dependent variable with some certainty. Without this element, one cannot use the results for predictive purposes. This is the most condemning evidence that risk assessment regarding the dangerousness of a person is not valid from a scientific point-of-view.
Every one of us is different, with different motivations, coping mechanisms, personalities, upbringings, social norms, and expectations. The individuality of every person makes it almost impossible to claim that the independent and dependent variables can be isolated. We all react differently, as individuals, to the situations that are presented. Not everyone will react in a predictable fashion when presented the exact same set of circumstances. Studies that involve the use of vignettes demonstrates this. One can develop general trends and norms within the population, sometimes with a considerable amount of accuracy, but no study to date has been developed that can predict with 100% certainty what a specific individual outcome will be.
It is simply not possible to predict accurately what an individual will do from one moment to the next. There are simply too many variables that can come into play. We can predict the most likely outcome, but the end result may surprise us. From this standpoint, risk assessment for dangerousness fails from an empirical standpoint. Many studies claiming to be predictive in nature are found to be lacking in one or more of these necessary elements for an empirical study. Let us now see what effect the use of risk assessment can have for individual court cases.
Risk Assessment in the Court Room
Despite the empirical shortcomings of the risk assessment methods examined, these general categories are still used in the courtroom. A prime example of the inadequacy of risk assessment and the use of "expert" witnesses is highlighted in Daubert v. Merrell Dow Pharmaceuticals (1993). In this case, a client had children born with severe birth defects, which he claimed were caused by ingestion of a product made by Dow Pharmaceuticals during her pregnancy. In this case the court ruled that "scientific evidence is admissible only if the principle upon which it is based is " 'sufficiently established to have general acceptance in the field to which it belongs' (Daubert v. Merrell Dow Pharmaceuticals (1993). This is a question that plagues the field of risk assessment on a daily basis.
In Fry vs. United States (1923), establishes that even when an error is found, such as imprisoning a person for potential violence, in order to be considered litigious a proof of harm must be produced. Simply proving the error is not enough, one must consider the injury caused by the error. In the case of risk assessment, this same principle applies. A certain risk is inherent in both the overestimation or underestimation of the dangerousness of a person. Courts often face the decision of deciding whether individual rights outweigh public risk.
Kumho Tire Co. v. Carmichael (1999) is one of the most famous risk assessment cases in the annals of law. In this case, a tire on Carmicheal's mini van blew out, causing a wreck in which one passenger was killed and several others severely injured. Carmichael sued for a defective tire. Carmichael lost based on the foundation established during Daubert v Merrell Dow Pharmaceuticals. The court ruled that causality could not be established because there were too many other variables that could have caused the accident, including the reactions of Carmichael himself. The dangerousness of the tire could not be established.
These court cases demonstrate the fallibility of risk assessment and the methods used to determine the dangerousness involved in a certain action. In the field of abnormal psychology, these principles have even greater weight. If the dangerousness of the person is judged too harshly, the person could lose their freedom and rights. It they err in the opposite direction, the public could be placed at risk. This examination of current methods and applications of risk assessment support the hypothesis that the prediction of dangerousness is not a science. It is found to be lacking in key elements of valid empirical research methodology. Therefore, risk assessment should only be used as a part of the picture. The whole of the decision should not rely on risk assessment and prediction alone.
Brown, M. & Pratt, J. 2000. Dangerous Offenders: Punishment and Social Order. New York: New York, Routledge Publishers.
Daubert v. Merrell Dow Pharmaceuticals (92-102), 509 U.S. 579 (1993). [online]
http://supct.law.cornell.edu/supct/html/92-102.ZO.html [Accessed March 25, 2009].
A de Barros DM, de Padua Serafim a. 2008. Association between personality disorder and violent behavior pattern. Forensic Sci Int 2008 Jun 2.
Dunkel, F. & van Zyl Smit, D. 2004. Preventive Detention of Dangerous Offenders Re- examined: A Comment on Two decisions of the German Federal Constitutional Court - Part II/II. German Law Journal. Vol 5, no 6 [online]
http://www.germanlawjournal.com/article.php?id=454 [Accessed March 25, 2009].
Fals-Stewart W, Leonard KE, & Birchler GR. 2005. The occurrence of male-to-female intimate partner violence on days of men's drinking: the moderating effects of antisocial personality disorder. J Consult Clin Psychol 2005 Apr; Vol 73, No 2. pp. 239-48.
Fry v. United States, 421 U.S. 542 (1975). [online]
http://supreme.justia.com/us/421/542 / [Accessed March 25, 2009].
Greenfeld LA, & Henneberg MA. 2001. Victim and offender self-reports of alcohol involvement in crime. Alcohol Res Health 2001; Vol 25, No 1. pp. 20-31.
Kennealy PJ, Hicks BM, & Patrick CJ. 2007. Validity of factors of the psychopathy checklist revised in female prisoners: discriminant relations with antisocial behavior, substance abuse, and personality. Assessment 2007 Dec; Vol. 14, No. 4. pp.:323-40.
Kumho Tire Co. v. Carmichael (97-1709) 526 U.S. 137 (1999)
Martens WH & Palermo GB. 2005. Loneliness and associated violent antisocial behavior: analysis of the case reports of Jeffrey Dahmer and Dennis Nilsen. Int J. Offender Ther Comp Criminol 2005 Jun; Vol.49, No. 3. pp. 298-307.
Nathan R, Rollinson L, Harvey K, & Hill J. 2003. The Liverpool Violence Assessment: an investigator-based measure of serious violence. Crim Behav Ment Health 2003; Vol. 13, No. 2. pp. 106-20.
Sobral J, Luengo a, & G. mez-Fraguela JA, et al. 2007. Personality, gender and violent criminality in prison inmates. Psicothema 2007 May; Vol. 19, No. 2. pp. 269-75.
Walsh Z, & Kosson DS. 2006. Psychopathy and Violent Crime: A Prospective Study of the Influence of Socioeconomic Status and Ethnicity. Law Hum Behav 2006 Nov 23.