Powers argues - erred in excluding testimony
The district court erred in excluding testimony of two experts
who would have testified that Powers did not exhibit the
characteristics of a fixated pedophile.
Fed. R. Evid. 702
Expert testimony explaining scientific evidence is admissible
under Fed. R. Evid. 702 if it will assist the jury "to
understand the evidence or determine a fact in issue."
When determining admissibility under Rule 702, a trial judge
must ensure that all scientific
testimony or evidence admitted is both relevant and
that its evidentiary
reliability is based upon scientific validity.
Daubert v. Merrell Dow Pharmaceuticals
The Daubert Court set forth a two-part test which must be met in
order for such expert testimony to be properly admitted under
The expert testimony must consist of "scientific knowledge"
-- that is, the testimony must be supported by appropriate
The evidence or testimony must "assist the trier of fact to
understand the evidence or to determine a fact in issue."
Whether the results of a penile plethysmograph test meet the
scientific validity prong of Daubert?
Powers argues - erred in excluding the testimony of a clinical
The district court erred in excluding the testimony of a
clinical psychologist who would have testified that the results
of a penile plethysmograph test did
not indicate that Powers exhibited pedophilic characteristics.
The penile plethysmograph, or arousal, test measured Powers'
sexual arousal in response to pictures of nude females of
various age groups.
The district court excluded
this evidence because, in its opinion, the test did not satisfy
the "scientific validity" prong of Daubert.
- Factors to evaluate the scientific validity
Whether the theory or technique used by the expert
can be, and has been, tested;
Whether the theory or technique has been
subjected to peer review and
The known or potential rate of error
of the method used; and
The degree of the method's or
conclusion's acceptance within the relevant
Discussing Factors in this case
First, the Government proffered evidence that the scientific
literature addressing penile plethysmography
does not regard the test as a valid
diagnostic tool because, although useful for
treatment of sex offenders, it has
no accepted standards in the scientific community.
Second, the Government also introduced evidence before the judge
that a vast majority of incest
offenders who do not admit their guilt, such as
Powers, show a normal reaction to the test.
Such false negatives render the test unreliable.
Powers failed to introduce any indicia, let alone a sufficient
level, of reliability to rebut the Government's evidence.
- district court abused its discretion concerning scientific
validity of the test.
Accordingly, in light of extensive, unanswered evidence weighing
against the scientific validity of the penile plethysmograph
test, we cannot say that the district court abused its
Daubert second prong - Whether the evidence will be helpful to
the trier of fact?
Powers argues - abused its discretion in excluding the testimony
of Dr. Sciara
The district court abused its discretion in excluding the
testimony of Dr. Anthony Sciara. Dr. Sciara would have testified
that Powers did not demonstrate the psychological profile of a
District Court - failed to establish relevant or scientific
The district court ruled that Powers failed to establish either
the relevance or the scientific validity of psychological
profiling as applied to the facts at issue.
Determining whether the evidence will be helpful to the trier
judge must be mindful of other evidentiary rules, such as
FRE 403, which permits
the exclusion of relevant
evidence "if its probative value is substantially outweighed by
the danger of unfair prejudice, confusion of the issues, or
misleading the jury."
Powers argues - Dr. Sciara's psychological profile of him meets
the relevancy criteria
Dr. Sciara's psychological profile of him meets the relevancy
criteria due to the direct relationship between the subject
matter of the test and the crime charged.
Counsel for Powers proffered the following evidence concerning
Dr. Sciara's psychological profile.
Based on numerous interviews with child sex abusers and other
research, Dr. Sciara has created a
profile of the common characteristics of incest abusers.
According to Sciara, the largest
common denominator among incest abusers is that forty
percent of the time they exhibit the characteristics of fixated
pedophiles. Powers' tests, however, revealed that he did not
share this characteristic.
Powers argues - testimony was clearly relevant
This testimony was clearly relevant for the purpose of
demonstrating that [he] was psychologically unlikely to have
committed the alleged crimes charged against him."
- We disagree.
- Powers fails to provide a link
Fails to provide a substantial link
between the expert testimony and his theory of defense.
At most, this evidence would have shown only that Powers did not
belong to a group that comprised forty percent of incest
Powers, however, was charged with statutory rape of his daughter
-- incest abuse -- not with being a fixated pedophile.
To be relevant, this testimony must show, in a very real way,
that because Powers did not share a characteristic common to a
large minority of incest perpetrators, he was less likely to be
an incest perpetrator himself.
- district court understood this flaw
The district court clearly understood this fundamental flaw when
the testimony was proffered:
How to supply the link
If Powers had offered supporting evidence
showing that those who are
not fixated pedophiles
are less likely to commit incest
abuse (the crime with which Powers was charged), Dr. Sciara's
testimony might have been relevant.
- Offered no evidence to link non-proclivity for pedophilia with
a non-proclivity for incest abuse
However, Powers offered no evidence to link a non-proclivity for
pedophilia with a non-proclivity for incest abuse, even after
the district court gave Powers ample opportunity to introduce
evidence showing the relevance of Dr. Sciara's testimony.
Accordingly, we find that the district court did not abuse its
discretion in excluding this evidence because Powers failed to
prove either its relevancy or "a valid scientific connection to
the pertinent inquiry" of whether he committed incest.