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Technique F73:Failure of Success Criterion 1.4.1 due to creating links that are not visually evident without color vision


Any technology.

This technique relates to 1.4.1: Use of Color (Failure).


The objective of this failure is to avoid situations in which people who cannot perceive color differences cannot identify links (when people with color vision can identify links). Link underlines or some other non-color visual distinction are required (when the links are discernible to those with color vision).

While some links may be visually evident from page design and context, such as navigational links, links within text are often visually understood only from their own display attributes. Removing the underline and leaving only the color difference for such links would be a failure because there would be no other visual indication (besides color) that it is a link.

Red and Pink are the same color (hue) but they have different lightness (which is not color ). So red and pink would pass the requirement for "not distinguished by color (hue) alone" since they differ by lightness (which is not color) - as long as the difference in lightness (contrast) is 3:1 or greater. For example, if surrounding text is RED and the link is PINK it would pass. Similarly a light green and a dark red differ BOTH by color AND by lightness so they would pass if the contrast (lightness) difference is 3:1 or greater before focus or pointing.

There is no requirement that links be identifiable by people who cannot perceive color if they are not perceivable for those with color vision. (e.g. if the links are hidden for everyone – as in a game or test).

If the non-color cue only happens when the mouse hovers over the link or when the link receives focus, it is still a failure.

If the link is a different color and bold it would not fail because the boldness is not color dependent.




  1. Check that each link in the page that is identifiable by color (hue) is visually identifiable via some other means (e.g., underlined, bolded, italicized, sufficient difference in lightness, etc).

Expected Results

  • If check #1 is false, then this failure condition applies and the content fails this Success Criterion.
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