Content validity need to make judgement in some systematic way. Content validity guarantees the candidates perform tasks which are genuinely the same or fundamentally similar to tasks one normally performs in exhibiting the skill or ability the tests purports to measure.
Content must consist of a representative sample of language structures and skills with which it is meant to be concerned, also leans towards high content validity. Content validity of a test, whilst being a necessity, is not an effective way of evaluating the test, due to not actually being able to give any evaluative information about the interpretation of test scores.