17 CFR § 166.2 - Authorization to trade.
No futures commission merchant, retail foreign exchange dealer, introducing broker or any of their associated persons may directly or indirectly effect a transaction in a commodity interest for the account of any customer unless before the transaction the customer, or person designated by the customer to control the account:
(a) With respect to a commodity interest as defined in any paragraph of the commodity interest definition in § 1.3 of this chapter, specifically authorized the futures commission merchant, retail foreign exchange dealer, introducing broker or any of their associated persons to effect the transaction (a transaction is “specifically authorized” if the customer or person designated by the customer to control the account specifies—
(1) The precise commodity interest to be purchased or sold; and
(2) The exact amount of the commodity interest to be purchased or sold); or
(b) With respect to a commodity interest as defined in paragraph (1) or (2) of the commodity interest definition in § 1.3 of this chapter, authorized in writing the futures commission merchant, introducing broker or any of their associated persons to effect transactions in commodity interests for the account without the customer's specific authorization; Provided, however, That if any such futures commission merchant, introducing broker or any of their associated persons is also authorized to effect transactions in foreign futures or foreign options without the customer's specific authorization, such authorization must be expressly documented.