Lately a 508 compliance issue came up. I started reading about some WCAG and 508 guidelines.
We see were the suggestions about at number ratio is talked about :
http://www.w3.org/TR/WCAG20/ 1.4.3 Contrast (Minimum): The visual presentation of text and images of text has a contrast ratio of at least 4.5:1, except for the following:
Is making contrast to at least 4.5.1 MANDATORY per the WCAG, to MEET 508 ... or is this a grey area where "compliance" vs. "accessibility" is the question?
First of all, all WCAG and 508 guidelines are mandatory. Failure of one guideline means that your document doesn't conform to the specifications. Where people get tripped up is that some guidelines are very subjective, for example reading level and cognition. You can easily argue that text is or isn't readable by different people making compliance in some areas an exercise in legalese.
However, color contrast is one of the few areas in the WCAG and 508 guidelines that is very objective. Color contrast is defined by WCAG as:
(L1 + 0.05) / (L2 + 0.05), where
L1 is the relative luminance of the lighter of the colors, and
L2 is the relative luminance of the darker of the colors.
So there is an algorithmic way of determining what the contrast ratio is, and additionally required contrast values are unambiguously stated: either 4.5:1 or 7:1 for AA or AAA compliance respectively.
In conclusion, no, this isn't a grey area, to meet 508 or WCAG compliance you must have adequate color contrast for all of your text.