You will already have the law that enables the regulation of the Agency. Use the US Code citation or the Statutes at Large Citation found in your case to look up the regulation of the Agency in the Index of the Code of Federal Regulations. Found in the Gov. Docs section: AE2.106/3-2:2011
Use the citation to look in the back of the index in the "Authorities" section. The US Code citations come first (USC) and the Statutes at Large Citation (Stat.) follow. Use the citation to find which part of the code to look at...21 USC 301 = 21 Part 1140 or 21 USC 321 = 21 Parts 1, 2, 3, 26, etc.
21 = the volume of the CFR to look in
Part = helps distinguish which volume and page to look at
For a great explanation of how to use these laws (citations) to find agency regulations, visit University of Minnesota's United States Laws and Legislation Guide linked below.
Be sure to cover the following...
1. Identify the Agency(s) involved in the Supreme Court case.
2. Discuss the legislation or order that created the Agency(s) and the range of powers and responsibilities it was given in the enabling act that created it.
3. What ruling or other action taken by the Agency(s) gave rise to the case brought before the Supreme Court.