X.2 and Effect X.2 has other causes in addition to Statute X, namely Factor 1
and Factor 2.
There now follows some illustrations of these complications. Some
illustrations come from law while others come from outside the field of law.
Separate and Independent Causes
One strand of Effect X.2 is constituted by Effect X.2A. Effect X.2A is part of
a chain of specific effects, which culminates in Effect X.nA.
Effect X.2A has two separate and independent causes, Effect X.1 (which is
caused by Statute X) and Factor 1. These operate in addition to each other
and not in combination. A useful illustration of two separate causes comes
from changes to the crime rate in the United States in the 1990s. While this did
not come from the operation of statute law it still serves as a useful illustration
of the concept of two independent causes of a phenomenon.
As the decade of the 1990s progressed, the crime rate fell and continued to
fall, confounding the expectations of many commentators. For example, by
2000 the overall murder rate was lower than it had been since 1965.
413
An
economist, Steven D Levitt, investigated this phenomenon in research, which
was published in 2005.
414
He considered the usual suspects for this reduction
in crime. Two well touted causes, greater use of the death penalty and different
policing methods, provided little or no explanation.
Two other causes, however, seemed to explain the drop in crime rate. One
was an increase in the length of sentences given to offenders while the other
was the decision of the United States Supreme Court in 1973 in the case of
Roe v Wade.
415
Increased Sentences
One explanation was increased sentences.
416
This explained some part of the
reduction in the crime rate, but not the major part. There are two
ways in
___________________
413
Levitt and Dubner (2005)
414
Levitt and Dubner (2005)
415
Roe v Wade 410 US 113 (1973)
416
It is interesting to pursue the chain of causation here. Much crime, at least
according to popular wisdom (and there is probably scientific grounding for this)
is committed by people who have already committed one or more crimes.
Therefore, increased jail time flowing from increased sentences keeps some of the
crime prone section of the population off the streets, that is, out of harm’s way, for
a longer time. This is called incapacitation. A second possible explanation, not
inconsistent with this, is that harsher sentences have a deterrent effect.
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