The law states:
"Web pages shall be designed so that all information conveyed with color is also available without color, for example from context or mark-up."
If you use color to present information, give your users another way to differentiate between your content. Vision impaired users will not be able to comprehend information with color.
For example, do not ask a user to "select an item from those listed in blue" or "fill in the required fields marked with red." Instead, give the items a name or mark the required fields with an asterisk.
The following example uses color incorrectly to identify important instructions. An easy solution is to mark required fields with asterisks instead of with color.
Bad use of color
Testing for Color Contrast
For testing techniques and tools, refer to Checkpoint C (color) in the CSU Cal Poly Section 508 Manual Website Evaluation Guide found in the Tools section of the Accessibility Compliance Guide.