42 USC 7605 - Representation in litigation

(a) Attorney General; attorneys appointed by Administrator 
The Administrator shall request the Attorney General to appear and represent him in any civil action instituted under this chapter to which the Administrator is a party. Unless the Attorney General notifies the Administrator that he will appear in such action, within a reasonable time, attorneys appointed by the Administrator shall appear and represent him.
(b) Memorandum of understanding regarding legal representation 
In the event the Attorney General agrees to appear and represent the Administrator in any such action, such representation shall be conducted in accordance with, and shall include participation by, attorneys appointed by the Administrator to the extent authorized by, the memorandum of understanding between the Department of Justice and the Environmental Protection Agency, dated June 13, 1977, respecting representation of the agency by the department in civil litigation.