Thirty-eight Nobel prize winning scientists and other notables have contacted the Kansas State Board of Education to request that they reject science standards that include intelligent design. The reason is simple: a model for the development of life that has, as its foundation, the involvement of a supernatural designer or planner (i.e. some sort of creator), cannot be tested by known scientific means. By definition, this type of model is not a scientific model.
Science deals with the physical universe, and its realm includes the study of natural processes. Proposed supernatural processes or entities is outside this realm, making it difficult to justify its inclusion in any science curriculum.