34 C.F.R.  §300.532.  Evaluation procedures.

Each public agency shall ensure, at a minimum, that the following requirements are met:

...

(e) Tests are selected and administered so as best to ensure that if a test is administered to a child with impaired sensory, manual, or speaking skills, the test results accurately reflect the child's aptitude or achievement level or whatever other factors the test purports to measure, rather than reflecting the child's impaired sensory, manual, or speaking skills (unless those skills are the factors that the test purports to measure).