Concerning the Graduate College: For exceptions to graduate college rules, it is possible to submit a petition to the Graduate Secretary. The Graduate College Handbook explains in detail when a petition is needed. Please consult with your advisor, the Director of Graduate Studies, and/or the Graduate Secretary regarding the specifics of petitioning.
Concerning departmental rules: Exceptions to departmental rules are given by the DGS; a "petition" for such an exemption is a less formal letter, and should be supported by the student's major advisor.