7 USC 6a - Excessive speculation

(a) Burden on interstate commerce; trading or position limits 
Excessive speculation in any commodity under contracts of sale of such commodity for future delivery made on or subject to the rules of contract markets or derivatives transaction execution facilities, or on electronic trading facilities with respect to a significant price discovery contract causing sudden or unreasonable fluctuations or unwarranted changes in the price of such commodity, is an undue and unnecessary burden on interstate commerce in such commodity. For the purpose of diminishing, eliminating, or preventing such burden, the Commission shall, from time to time, after due notice and opportunity for hearing, by rule, regulation, or order, proclaim and fix such limits on the amounts of trading which may be done or positions which may be held by any person under contracts of sale of such commodity for future delivery on or subject to the rules of any contract market or derivatives transaction execution facility, or on an electronic trading facility with respect to a significant price discovery contract, as the Commission finds are necessary to diminish, eliminate, or prevent such burden. In determining whether any person has exceeded such limits, the positions held and trading done by any persons directly or indirectly controlled by such person shall be included with the positions held and trading done by such person; and further, such limits upon positions and trading shall apply to positions held by, and trading done by, two or more persons acting pursuant to an expressed or implied agreement or understanding, the same as if the positions were held by, or the trading were done by, a single person. Nothing in this section shall be construed to prohibit the Commission from fixing different trading or position limits for different commodities, markets, futures, or delivery months, or for different number of days remaining until the last day of trading in a contract, or different trading limits for buying and selling operations, or different limits for the purposes of paragraphs (1) and (2) of subsection (b) of this section, or from exempting transactions normally known to the trade as spreads or straddles or arbitrage or from fixing limits applying to such transactions or positions different from limits fixed for other transactions or positions. The word arbitrage in domestic markets shall be defined to mean the same as spread or straddle. The Commission is authorized to define the term international arbitrage.
(b) Prohibition on trading or positions in excess of limits fixed by Commission 
The Commission shall, in such rule, regulation, or order, fix a reasonable time (not to exceed ten days) after the promulgation of the rule, regulation, or order; after which, and until such rule, regulation, or order is suspended, modified, or revoked, it shall be unlawful for any person
(1) directly or indirectly to buy or sell, or agree to buy or sell, under contracts of sale of such commodity for future delivery on or subject to the rules of the contract market or markets, or derivatives transaction execution facility or facilities or electronic trading facility with respect to a significant price discovery contract, to which the rule, regulation, or order applies, any amount of such commodity during any one business day in excess of any trading limit fixed for one business day by the Commission in such rule, regulation, or order for or with respect to such commodity; or
(2) directly or indirectly to hold or control a net long or a net short position in any commodity for future delivery on or subject to the rules of any contract market or derivatives transaction execution facility or electronic trading facility with respect to a significant price discovery contract in excess of any position limit fixed by the Commission for or with respect to such commodity: Provided, That such position limit shall not apply to a position acquired in good faith prior to the effective date of such rule, regulation, or order.
(c) Applicability to bona fide hedging transactions or positions 
No rule, regulation, or order issued under subsection (a) of this section shall apply to transactions or positions which are shown to be bona fide hedging transactions or positions as such terms shall be defined by the Commission by rule, regulation, or order consistent with the purposes of this chapter. Such terms may be defined to permit producers, purchasers, sellers, middlemen, and users of a commodity or a product derived therefrom to hedge their legitimate anticipated business needs for that period of time into the future for which an appropriate futures contract is open and available on an exchange. To determine the adequacy of this chapter and the powers of the Commission acting thereunder to prevent unwarranted price pressures by large hedgers, the Commission shall monitor and analyze the trading activities of the largest hedgers, as determined by the Commission, operating in the cattle, hog, or pork belly markets and shall report its findings and recommendations to the Senate Committee on Agriculture, Nutrition, and Forestry and the House Committee on Agriculture in its annual reports for at least two years following January 11, 1983.
(d) Persons subject to regulation; applicability to transactions made by or on behalf of United States 
This section shall apply to a person that is registered as a futures commission merchant, an introducing broker, or a floor broker under authority of this chapter only to the extent that transactions made by such person are made on behalf of or for the account or benefit of such person. This section shall not apply to transactions made by, or on behalf of, or at the direction of, the United States, or a duly authorized agency thereof.
(e) Rulemaking power and penalties for violation 
Nothing in this section shall prohibit or impair the adoption by any contract market, derivatives transaction execution facility, or by any other board of trade licensed, designated, or registered by the Commission or by any electronic trading facility of any bylaw, rule, regulation, or resolution fixing limits on the amount of trading which may be done or positions which may be held by any person under contracts of sale of any commodity for future delivery traded on or subject to the rules of such contract market or derivatives transaction execution facility or on an electronic trading facility, or under options on such contracts or commodities traded on or subject to the rules of such contract market, derivatives transaction execution facility, or electronic trading facility or such board of trade: Provided, That if the Commission shall have fixed limits under this section for any contract or under section 6c of this title for any commodity option, then the limits fixed by the bylaws, rules, regulations, and resolutions adopted by such contract market, derivatives transaction execution facility, or electronic trading facility or such board of trade shall not be higher than the limits fixed by the Commission. It shall be a violation of this chapter for any person to violate any bylaw, rule, regulation, or resolution of any contract market, derivatives transaction execution facility, or other board of trade licensed, designated, or registered by the Commission or electronic trading facility with respect to a significant price discovery contract fixing limits on the amount of trading which may be done or positions which may be held by any person under contracts of sale of any commodity for future delivery or under options on such contracts or commodities, if such bylaw, rule, regulation, or resolution has been approved by the Commission or certified by a registered entity pursuant to section 7a–2 (c)(1) of this title: Provided, That the provisions of section 13 (a)(5) of this title shall apply only to those who knowingly violate such limits.