Definition · Plain-language
Deviation
A deviation is any departure from an approved instruction, procedure, specification or established standard within a regulated process — an unplanned event that must be documented and investigated.
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What counts as a deviation
A deviation is any departure from what was approved — a procedure not followed exactly, a process parameter outside its defined range, a specification not met, or an established practice not observed. Deviations can arise from human action, equipment failure, material issues or environmental conditions. The key point is that the system does not pretend deviations never happen; instead it requires that when they do occur they are openly recorded, assessed and investigated, rather than ignored or quietly corrected, which would itself be a serious data-integrity failure.
Investigation, classification and impact
When a deviation is raised, its potential impact on product quality, safety and data integrity is assessed, and the event is typically classified by severity — often critical, major or minor — to guide the depth of response. An investigation establishes what happened and why, using root cause analysis for significant deviations. The product affected may be placed on hold pending a decision. The outcome documents the impact assessment, the root cause and the disposition of any affected product, providing a defensible record for review and inspection.
Deviations, CAPA and change control
Deviation management connects to the wider quality system. A significant deviation usually triggers CAPA: corrective action to address the immediate cause and preventive action to stop recurrence. By contrast, a deviation is not the mechanism for making intentional changes — those go through change control. The term “planned deviation” is sometimes used for a pre-approved, temporary departure, but many quality systems now prefer to handle such situations through change control to avoid blurring the line between unplanned events and intentional change.
Key facts
At a glance
- Definition: a departure from an approved procedure, specification or standard
- Requirement: documented, impact-assessed and investigated
- Classification: typically by severity (e.g. critical, major, minor)
- Investigation tool: root cause analysis for significant deviations
- Common outcome: corrective and preventive action (CAPA)
- Distinct from: change control, which governs intentional changes
Common misconceptions
What people often get wrong
Often heard: A minor deviation can just be corrected quietly without recording it.
Actually: All deviations must be documented, assessed and investigated. Quietly correcting a departure without recording it is itself a serious data-integrity failure, not a shortcut. Open recording is fundamental to a sound quality system.
Often heard: A deviation is how you make an intentional change to a process.
Actually: Intentional changes go through change control, not deviation management. A deviation is an unplanned departure that has already occurred. Using a deviation to introduce a change blurs the line between unplanned events and managed change.
Often heard: Once a deviation is recorded, no further action is needed.
Actually: Recording is only the start. A deviation must be impact-assessed, investigated for root cause and, where appropriate, addressed through CAPA to prevent recurrence. Significant deviations also determine the disposition of affected product.
Going deeper
