15 U.S.C. § 717c : US Code - Section 717C: Rates and charges

    (a) Just and reasonable rates and charges
      All rates and charges made, demanded, or received by any natural-
    gas company for or in connection with the transportation or sale
    of natural gas subject to the jurisdiction of the Commission, and
    all rules and regulations affecting or pertaining to such rates or
    charges, shall be just and reasonable, and any such rate or charge
    that is not just and reasonable is declared to be unlawful.
    (b) Undue preferences and unreasonable rates and charges prohibited
      No natural-gas company shall, with respect to any transportation
    or sale of natural gas subject to the jurisdiction of the
    Commission, (1) make or grant any undue preference or advantage to
    any person or subject any person to any undue prejudice or
    disadvantage, or (2) maintain any unreasonable difference in rates,
    charges, service, facilities, or in any other respect, either as
    between localities or as between classes of service.
    (c) Filing of rates and charges with Commission; public inspection
      of schedules
      Under such rules and regulations as the Commission may prescribe,
    every natural-gas company shall file with the Commission, within
    such time (not less than sixty days from June 21, 1938) and in such
    form as the Commission may designate, and shall keep open in
    convenient form and place for public inspection, schedules showing
    all rates and charges for any transportation or sale subject to the
    jurisdiction of the Commission, and the classifications, practices,
    and regulations affecting such rates and charges, together with all
    contracts which in any manner affect or relate to such rates,
    charges, classifications, and services.
    (d) Changes in rates and charges; notice to Commission
      Unless the Commission otherwise orders, no change shall be made
    by any natural-gas company in any such rate, charge,
    classification, or service, or in any rule, regulation, or contract
    relating thereto, except after thirty days' notice to the
    Commission and to the public. Such notice shall be given by filing
    with the Commission and keeping open for public inspection new
    schedules stating plainly the change or changes to be made in the
    schedule or schedules then in force and the time when the change or
    changes will go into effect. The Commission, for good cause shown,
    may allow changes to take effect without requiring the thirty days'
    notice herein provided for by an order specifying the changes so to
    be made and the time when they shall take effect and the manner in
    which they shall be filed and published.
    (e) Authority of Commission to hold hearings concerning new
      schedule of rates
      Whenever any such new schedule is filed the Commission shall have
    authority, either upon complaint of any State, municipality, State
    commission, or gas distributing company, or upon its own initiative
    without complaint, at once, and if it so orders, without answer or
    formal pleading by the natural-gas company, but upon reasonable
    notice, to enter upon a hearing concerning the lawfulness of such
    rate, charge, classification, or service; and, pending such hearing
    and the decision thereon, the Commission, upon filing with such
    schedules and delivering to the natural-gas company affected
    thereby a statement in writing of its reasons for such suspension,
    may suspend the operation of such schedule and defer the use of
    such rate, charge, classification, or service, but not for a longer
    period than five months beyond the time when it would otherwise go
    into effect; and after full hearings, either completed before or
    after the rate, charge, classification, or service goes into
    effect, the Commission may make such orders with reference thereto
    as would be proper in a proceeding initiated after it had become
    effective. If the proceeding has not been concluded and an order
    made at the expiration of the suspension period, on motion of the
    natural-gas company making the filing, the proposed change of rate,
    charge, classification, or service shall go into effect. Where
    increased rates or charges are thus made effective, the Commission
    may, by order, require the natural-gas company to furnish a bond,
    to be approved by the Commission, to refund any amounts ordered by
    the Commission, to keep accurate accounts in detail of all amounts
    received by reason of such increase, specifying by whom and in
    whose behalf such amounts were paid, and, upon completion of the
    hearing and decision, to order such natural-gas company to refund,
    with interest, the portion of such increased rates or charges by
    its decision found not justified. At any hearing involving a rate
    or charge sought to be increased, the burden of proof to show that
    the increased rate or charge is just and reasonable shall be upon
    the natural-gas company, and the Commission shall give to the
    hearing and decision of such questions preference over other
    questions pending before it and decide the same as speedily as
    possible.
    (f) Storage services
      (1) In exercising its authority under this chapter or the Natural
    Gas Policy Act of 1978 (15 U.S.C. 3301 et seq.), the Commission may
    authorize a natural gas company (or any person that will be a
    natural gas company on completion of any proposed construction) to
    provide storage and storage-related services at market-based rates
    for new storage capacity related to a specific facility placed in
    service after August 8, 2005, notwithstanding the fact that the
    company is unable to demonstrate that the company lacks market
    power, if the Commission determines that - 
        (A) market-based rates are in the public interest and necessary
      to encourage the construction of the storage capacity in the area
      needing storage services; and
        (B) customers are adequately protected.

      (2) The Commission shall ensure that reasonable terms and
    conditions are in place to protect consumers.
      (3) If the Commission authorizes a natural gas company to charge
    market-based rates under this subsection, the Commission shall
    review periodically whether the market-based rate is just,
    reasonable, and not unduly discriminatory or preferential.