One of the
things about the death penalty is that the Supreme Court of the United States
has held that no legitimate penological purpose is served by executing the
intellectually disabled: Atkins v
Virginia, 536 U.S. 304, 312 (2002).
So, what does
“intellectually disabled” mean? Currently the medical community defines it as
the existence of concurrent deficits in intellectual and adaptive functioning.
The courts regard it as proper to consult the medical community’s opinions when
it is necessary to come up with a definition.
In Hall v Florida, USSC No 12-10882,
27 May 2014 the issue was whether interpretation by the Florida Supreme Court
of legislation, that could be read consistently with the USSC’s caselaw, was
constitutional. The Florida court had held that intellectual disability
requires an IQ of 70 or less. Mr Hall scored 71 (although as the USSC
dissenters in Hall point out he had
actually had several tests in which he scored higher). The case is not
concerned with what “adaptive functioning” means, only with what
“intellectually” means in the expression “intellectually disabled”.
The majority,
Kennedy J, joined by Ginsburg, Breyer, Sotomayor, and Kagan JJ, held that the
requirement for a score of 70 or under was unconstitutional because it ignored
the margin of error inherent in testing. When a score of 70 is within the
margin of error, the defendant should pass the first requirement and then have
the opportunity to present evidence of lack of adaptive functioning. The
decision of the Florida Supreme Court was reversed and the case remanded for
determination consistent with the majority’s opinion.
The minority,
Alito J, joined by Roberts CJ, Scalia and Thomas JJ, dissented on the grounds
that the Florida court’s interpretation was reasonable because it allowed the
defendant to present several IQ test scores, and it is known that accuracy
increases when more than one test score is considered. The majority’s opinion
introduced uncertainty, as to what scores could come within the range that
passed the first requirement, and as to how courts should deal with changing
medical opinion as to what score indicates intellectual disability. The law
should apply society’s standards, not those of a professional body, and the
proper focus is on whether the defendant is able to understand the possibility
of execution as a penalty notwithstanding diminished ability to comprehend and
process information, to learn from experience, to reason logically, or control
impulses.
The minority
criticised the majority’s method of counting the states when assessing what
public opinion regards as appropriate, and pointed out that the majority did
not address why Florida’s method of accounting for the risk of test error (by
allowing more than one test to be considered) was ineffective.
There is
plenty of interesting discussion of IQ testing in this case. The average IQ is
100, a standard deviation is about 15, and two standard deviations below
average is taken to be 70, the upper limit for being intellectually disabled (more accurately: the upper limit for meeting the "intellectually" limb of the description "intellectually disabled").
But a test score comes with a range of error, and a person who scores 70 may
really have an IQ between 65 and 75, but the range varies according to the
range applicable for a given test and the extent to which one wishes to be sure
of the result (that is, the degree of confidence). Some tests may carry a lower
range of error, so that one could say with a high degree of confidence that a
person who scored 70 really had an IQ between, for example, 68 and 72.
An
interesting point, from a lawyer’s perspective, was made in the dissent: before
this decision, a defendant had to satisfy the court on the balance of
probabilities that his IQ was 70 or less. Now, if a defendant may have an IQ in
a range that includes 70, he is entitled to go on to produce evidence of his
lack of adaptive functioning. The standard of proof is, say the minority,
altered.
I note (this
is me now, not the Court) that in law we often receive scientific test results
without reference to a range of error or a confidence interval. For example,
regimes for testing in alcohol-related driving cases usually involve a test
result which the defendant can challenge by independent analysis of a blood
sample, where one has been taken. It is usual for the prosecutor's analysis laboratory to
knock off a bit of the alcohol result just to be safe, so that even if the
final reported level is just over the limit, an independent result would
probably be higher. If a defendant facing a penalty for an alcohol-related
driving offence has an opportunity to challenge the test result, so should a
defendant facing the death penalty. Obviously everyone would agree with that.
The analogy suggests that it is not necessary to express an IQ score as being
within a range of error or as being within a given confidence interval.
Some test
results received by courts, such as DNA results, are stated in probabilistic
terms, and rightly so. If one were to require a probabilistic report of an IQ
test score, one would look for some statistic such as a likelihood ratio: the
probability of getting this score, given that that was the defendant’s IQ,
compared to the probability of getting that score, given that that was not his
IQ. But I suspect that the confidence interval says the same thing, and the
question becomes, do courts really need that extra information?
If the
reasoning of the majority in Hall
were to be applied to evidence of the result of a blood test for alcohol, the
effect would be to remove the legal limit. If, as I do, you instinctively side
with the majority in cases like Hall,
you still have to deal with the logic of the dissent. Instead of ignoring it, like the majority here, you could accept that sometimes in law logic is trumped by experience, and do as the Privy Council majority did in Ramdeen v The State (Trinidad and Tobago) noted here on 28 March 2014.
