By: Elise Magnuson, PsyD, MSW, LSCW


Courts and other decision making bodies often want information regarding the likelihood of recidivism of someone who has committed a sex offense.   Nobody can tell the future and so nobody can tell you if someone will or will not engage in a behavior. Because of this, many in the field have moved away from risk prediction to risk assessment and management.  However, having an experienced psychosexual expert witness evaluate the individual is crucial to achieve an optimal result. This expert witness can provide all parties with the following: a clinical interview, record review, tests and measures, and detailed conclusions and recommendations. By describing the risk and ways to manage it psychosexual expert witnesses can provide decision makers with information that may be helpful to them.


When assessing risk there are two general approaches, nomothetic and ideographic.  Nomothetic measures for risk of recidivism are actuarial measures that are developed much like car insurance.  Individuals are rated on a number of items such as their age, past convictions, past convictions of sexual offense, and marital status.  The ratings are combined for a score and then one can compare a specific individual to others who received the same score.  It does not tell you if the individual will reoffend, just how often people with the same number have reoffended.  The Static-99-R and the SORAG are common examples of actuarial measures used to assess risk of recidivism in adult sex offenders.

Limitations on Actuarial Measures

One of the limitations of actuarial measures is there is very little the offender can do to change his score besides getting older or having a long term stable relationship (like a marriage) because most of the items are historical.  This means once someone is high risk, they are always high risk.  It also does not capture some situations such as where someone says, “I am going to sexually offend again.”

Dynamic Risk Factors

Structured Clinical Judgment approaches allow for looking at a person’s current functioning as well as their history.  These tools were developed by looking at the literature and consider current functioning as well as historical factors.  Unlike the actuarial measures, these tools do not give a number and the evaluator makes the judgment of high, medium, or low risk.  Two examples are the SVR-20 and the Stable and Acute.  Both allow for assessing current functioning in areas that research suggest are linked to recidivism such as drug and alcohol abuse, relationship problems, emotional problems and employment.  These areas are called dynamic risk factors because they change over time.  Assessing these areas can augment the nomothetic approach by taking into account the current situation.

Ideographic Methods

Ideographic methods are a purely individual way of looking at the person.  In this method the evaluator looks at the situation the person was in and how the person was thinking and feeling when they offended.  By doing a careful analysis the evaluator can identify patterns that lead to this person sexual offending.  This is very helpful when developing treatment plans.  However, is does not allow for comparative ranking of risk.

When the expert witness has both the nomothetic and ideographic data they can make a relative risk statement.  Good assessments will discuss both sources of information and draw a conclusion.  This is easy when the tools are in agreement, but more difficult when they appear in conflict.  The assessment should explain the difference and how the evaluator came to their conclusions.


Once a relative risk has been determined, the risk management plan can be developed.   Using the dynamic risk factors and the identified patterns from the ideographic analysis, the psychosexual expert witness can develop a plan that targets those areas where change would help lower the offender’s risk to reoffend.

About the Author

Elise C. Magnuson, PsyD, MSW, LCSW is a forensic psychologist and expert witness who specializes in risk assessment, psychosexual, and sex offender issues.