Abnormal use

The word that matters is deliberate. A mistake by a user is a use error and belongs in the usability and risk work, while abnormal use is outside the manufacturer's reasonable control. Calling a use error abnormal use so that it can be left out of the risk work is something reviewers look for.

conscious, deliberate act or deliberate omission of an act that is counter to or violates NORMAL USE and is also beyond any further reasonable means of USER INTERFACE-related RISK CONTROL by the MANUFACTURER EXAMPLES Reckless use or sabotage or deliberate disregard of information for SAFETY are such acts. Note 1 to entry See also 4.1.3. Note 2 to entry: An intended but erroneous action that is not ABNORMAL USE is considered a type of USE ERROR. Note 3 to entry: ABNORMAL USE does not relieve the MANUFACTURER from considering non-USER INTERFACE-related means of RISK CONTROL. Note 4 to entry: Figure 1 shows the relationships of the types of use.

IEC 62366-1:2015+AMD1:2020, clause 3.1

‘Abnormal use’ is the deliberate violation of the intended use of a device. It is a deliberate act or omission of an act by the user that is counter to or violates the normal use of a device and is beyond any further reasonable means of interface-related risk control measures by the manufacturer.

MDCG 2023-3 Rev.2, Question 5

Conscious, deliberate act or deliberate omission of an act that is counter to or violates normal use and is also beyond any further reasonable means of user interface-related risk control by the manufacturer.

FDA guidance: Applying Human Factors and Usability Engineering to Medical Devices (August 2026), Section 3, Definitions