Article XI, section 9 of the Hawai'i Constitution guarantees each person 'the right to a clean and healthful environment, as defined by laws relating to environmental quality.' Article I, section 5 provides that '[n]o person shall be deprived of life, liberty or property without due process of law.' This case involves a power purchase agreement. Maui struck a deal with the Hawaiian Commercial & Sugar Company (HC&S), a producer of electricity. Under Hawaii Revised Statutes (HRS) § 269-16.22, relating to power purchase agreements, Maui was allowed to recover all power purchase costs from customers subject to the approval of the Public Utilities Commission (PUC). Maui filed its application with the PUC seeking approval of the HC&S deal. Maui sought the PUC's approval that the energy charges to be incurred were just and reasonable, a finding that the Agreement was prudent and in the public interest, and an authorization to charge consumers for the energy costs through its existing energy cost adjustment clause. The HC&S facility located in Pu'unene consisted of a sugar processing operation with an internal bagasse-fired power plant that also burned a number of other fuels, including coal and petroleum as well as sugar cane pulp. The Sierra Club filed a motion to intervene on behalf of itself and its members who live in close proximity to the Pu'unene Plant. Sierra asserted a due process right on the grounds that the Agreement would impact its members' health, aesthetic, and recreational interests. Sierra Club members were concerned that the Plant relied too heavily on coal and the public health and visibility impacts of burning coal. It claimed that members were forced to close the windows of their homes and run air filters to protect against harmful pollution. It noted that the Department of Health sought to impose a fine of over one million dollars on HC&S in the previous year as a result of more than four hundred violations of the Clean Air Act. Sierra claimed the plant operated without modern pollution controls and consistently violated limits set by the Clean Air Act. The Sierra Club attached the affidavits of two of their members to the motion for intervention or participation. PUC denied Sierra Club's motion to intervene or to participate without considering Sierra Club's due process assertion. It held that Sierra Club did not have an interest distinct from the general public and that 'its interests in environmental issues and impacts could unreasonably broaden the issues already presented.' The PUC denied Sierra Club's motion for reconsideration. The Commission granted the Application to approve the Agreement. Sierra Club appealed to the Intermediate Court of Appeals (ICA). The ICA granted Maui's motion to dismiss. The Sierra Club filed an application for a writ of certiorari to the Hawai'i Supreme Court.