17 CFR 38.350 - Core Principle 6.
The board of trade, in consultation or cooperation with the Commission, shall adopt rules to provide for the exercise of emergency authority, as is necessary and appropriate, including the authority:
(a) To liquidate or transfer open positions in any contract;
(b) To suspend or curtail trading in any contract; and
(c) To require market participants in any contract to meet special margin requirements.