Complex or inaccessible language
Payment step changes language without warning
A fictional shop presents product and basket information in English but switches mandatory fee and return text to another language on the payment screen.
Individual HTML example · Interface interference
Cancellation consequence written in legalese
A fictional service describes the effect of cancellation through a 220-word clause containing undefined terms and cross-references immediately before confirmation.
This is an original fictional comparison. It depicts no real company and is not a legal finding or safe harbour.
Cancellation consequence written in legalese
A fictional service describes the effect of cancellation through a 220-word clause containing undefined terms and cross-references immediately before confirmation.
Effectuation of cessation. Undefined legal terms obscure what happens after the button is pressed.. Acknowledge cessation provision. End plan
Your plan ends on 30 September. No further renewal; files remain available until that date.. End plan. Acknowledge cessation provision. What happens next, expanded: Activating “End plan” produces the outcome stated on the control.
Why the first version can mislead: The presentation changes what the user can notice or predict at the cancellation decision. The problematic state shows: “Undefined legal terms obscure what happens after the button is pressed.” Its influence should be tested by comparing the consequence and usability of “Acknowledge cessation provision” with “End plan”. A subscriber may not understand billing, access or data consequences at the moment of choice.
What a fairer design does: Summarise the effective date, final charge, remaining access and data outcome in plain language, with legal detail available separately.
Show annotated differences (2)
Potentially problematic version
- End planIn “Cancellation consequence written in legalese”, this element shows how complex or inaccessible language can shape the decision.
Neutral alternative
- What happens next, expanded: Activating “End plan” produces the outcome stated on the control.In “Cancellation consequence written in legalese”, this element keeps the clearer alternative visible at the same decision point.
Review questions (3)
- Do “Acknowledge cessation provision” and “End plan” receive comparable prominence and explain their consequences before activation?
- Can the dialog be dismissed, what action does each control trigger, and what later state confirms or contradicts “The text is material to a decision”?
- What neutral rendering or comprehension result would falsify the classification, particularly in light of “Necessary technical terminology with clear explanation”?
Complete pattern context
How this example relates to Complex or inaccessible language
Material guidance is presented in a language or level of complexity that makes informed choice materially harder for the target user. The label describes a recurring design mechanism; whether a particular implementation is harmful or unlawful depends on the complete journey, audience, evidence and rules within scope.
The full guide explains inclusion and exclusion criteria, harms, fair design principles, evidence questions and the relevant EU legal information layers. The example page isolates one scenario so it can be shared and discussed without reproducing the complete library on one page.
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Ticket and travel pass presented as one package
A fictional ticket seller offers a concert ticket only through a control that also adds a city travel pass, although the travel component is separately deliverable and not required for entry.
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Support and migration locked into one plan
A fictional service offers a core plan only as a bundle with premium support and data migration, while implying those extras can be removed later although no controls exist.
Sources and provenance for this example
Evidence base
Sources
- An Ontology of Dark Patterns KnowledgeGray et al.; ACM CHI 2024 · Secondary · checked 2026-09-14 · DOI 10.1145/3613904.3642436; arXiv:2309.09640
- Unfair Commercial Practices DirectiveEuropean Parliament and Council of the European Union · Primary · checked 2026-08-09 · Directive 2005/29/EC; CELEX 02005L0029-20220528