Expert Witness Journal Issue 67 June/July 2026 - Flipbook - Page 77
Why “User Error” Is Rarely the
Root Cause of Workplace Injury
by Adam King, EUR ING, MSc, CEng, TechIOSH, MIAAI, Associate Director,
Forensic Investigation and Personal Injury at RIMKUS.
Courts increasingly require an analysis of whether:
In workplace personal injury claims involving work
equipment, an employer frequently cites “user error”
as the cause of an incident. While user actions often
feature in the 昀椀nal moments of an incident, forensic
engineering investigations consistently demonstrate
that user error is rarely the root cause. This article
looks at why courts, regulators, and insurers
increasingly expect an engineering‑led analysis of
causation, and why reliance on “user error” alone
presents both litigation and indemnity risk.
•
•
•
•
From a forensic perspective, reliance on user error
alone risks oversimpli昀椀cation and can weaken a
claim’s defensibility.
Introduction:
The persistence of “user error”
The distinction: Immediate cause,
underlying cause and root cause
From initial noti昀椀cation through to early expert
instruction, claims documentation frequently
characterises workplace incidents using phrases
such as:
•
•
•
A recurring issue in personal injury claims is
the confusion among three distinct concepts:
immediate, underlying and root cause. These terms
are often used interchangeably in claims narratives,
despite having materially di昀昀erent meanings within
an engineering‑led causation analysis.
The operator misused the equipment
The injured party failed to follow the training
The employee failed to follow the employer’s
instructions.
•
Although
such
descriptions
may
appear
straightforward, they are increasingly vulnerable
to challenge under forensic and legal scrutiny. In
litigation, courts now move beyond these surface
explanations and ask a more fundamental question:
why was the system capable of producing harm at
all?
•
•
Immediate Cause: The immediate action
preceding the injury
Underlying Cause: The means by which the
work equipment was able to cause harm
Root cause: The reason the hazardous condition
existed.
For example:
•
Forensic investigations across machinery operation,
maintenance activities, and industrial environments
have demonstrated that user action is typically the
昀椀nal link in a longer causal chain, rather than the
initiating failure. These statements may describe
what occurred, but they do not explain why injury
was possible.
EXPERT WITNESS JOURNAL
The equipment was inherently safe by design
The incident was foreseeable
Were engineering controls su昀케cient and
correctly implemented
Did the system rely excessively on procedural
compliance rather than physical safeguards and
supervision?
•
•
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Immediate Cause: The operator’s hand entered
the danger zone
Underlying Cause: Exposure to unguarded
moving parts
Root cause: Inadequate guarding, ine昀昀ective
interlocking, or unsafe by design
JUNE 2026
