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"Absence
of proof is not proof of absence" [ attributed to William Cowper
1731-1800] Society of Expert Witnesses Conference on
"Immunity and Uncertainty" Studely Castle Warwickshire on Friday
October 6th 2006 The
recent
widespread introduction of automobile
electronic control systems - for
example, electronic throttle control, anti-lock braking and automatic
stability
systems - has fundamentally altered the relationship between driver and
vehicle. The driver now
controls the vehicle indirectly
by means of a number of surrogate electronic control systems, which may
exhibit
a will of their own and a capability to respond unpredictably and
sometimes
dangerously. A system designed to control speed may malfunction and
cause a
loss of speed control. A system designed to improve vehicle stability
may cause
the vehicle to become unstable. Intermittent electronic system
malfunctions often caused by electromagnetic interference or software
glitches - are
notoriously difficult to diagnose because, unlike hardware faults, they
leave
little trace behind them afterwards. Switch a malfunctioning electronic
system
off and on again and it resets and behaves normally for days, weeks,
months or
even years. Attempts to reproduce the failure mode are often fruitless.
However, failure to diagnose or reproduce the malfunction does not mean
that
the malfunction never occurred, in other words: "Absence
of proof is not proof of absence". In fact the only
proof of the incident may lie in the characteristics of the event
itself.
Unfortunately, in the courts absence of proof may well be accepted as
proof of
absence: i.e. if no physical evidence can be found of an electronic
malfunction
then there can have been no electronic malfunction: ergo it must have
been the
driver who was at fault. Antony
Anderson uses examples from his electrical and electronic casework to
illustrate how "Absence of proof is not proof of
absence". Hopefully he
will
stimulate discussion on how to minimize the risk of drivers unjustly
carrying
the can for the occasional, but inevitable, intermittent malfunctions
of
safety-critical automobile electronic control systems.
Return to Section 6 : Frequency of sudden unintended acceleration incidents and alleged examples |