All agencies have to interpret their enabling legislation to determine what they can legally do. If the legislation is clear and detailed, the agency’s role will be easy to determine and there will be little controversy over the interpretation of the law. In many cases, however, the enabling legislation is complex and ambiguous, and sometimes has internal contradictions. The agency must make its best guess as to the meaning of the law, and anticipate that it will be challenged in the courts. Even when the law is clear, the agency may have to respond to pressure from the president to or from Congress regulate in ways that are questionable under the law. Wherever an agency is operating beyond the clear limits of its enabling legislation, it can expect to have its actions challenged in court because such challenge does not require the litigant to exhaust the agency procedures and thus expose itself to agency sanction as the price of appeal.

The courts do not defer to agencies’ interpretation of laws because that is the area of the courts’ expertise. It is not unusual for a court to prohibit an agency from regulating an activity because Congress did not give the agency authority for the contested regulations. For example, when the FDA tried to restrict a physician’s right to give patients his homemade drugs, the court found that the agency’s enabling legislation did not give it the power to regulate medical practice. The courts will also intervene if the agency actions, even if authorized by the enabling legislation, violate constitutional protections, as in the Goldberg case on the rights of persons being denied government benefits.