Answer: regulation
Explanation:
Citizens are allowed to sue federal administrative agencies who are empowered to make specialized rules and regulations that would enable them to properly enforce the mandate given to them by Congress.
Of course one cannot just sue at the first instance, there must have been a series of appeals to various bodies within this agency to repeal the rule or regulation that is causing grief. If those bodies refuse and it is found that the agency did not act in good faith in making the rule, the court will hear an appeal on the matter without exhaustion.
