47 U.S.C. § 211: Contracts of carriers; filing with Commission

(a) Every carrier subject to this chapter shall file with the Commission copies of all contracts, agreements, or arrangements with other carriers, or with common carriers not subject to the provisions of this chapter, in relation to any traffic affected by the provisions of this chapter to which it may be a party. (b) The Commission shall have authority to require the filing of any other contracts of any carrier, and shall also have authority to exempt any carrier from submitting copies of such minor contracts as the Commission may determine.