NERSA is mandated under the Gas Act to regulate gas prices where there is inadequate competition. Sasol Gas (Pty) Ltd held a monopoly in the South African piped-gas market and charged prices based on "market value pricing" under the Mozambican Gas Pipeline Agreement, which allowed it to price gas just below each customer's cost of switching to alternative fuels. This regime ended on 25 March 2014. NERSA determined there was inadequate competition and Sasol applied for approval of maximum gas prices and transmission tariffs. NERSA approved Sasol's applications on 26 March 2013 using a "basket of alternatives" methodology that referenced prices of coal, diesel, electricity, HFO and LPG. The respondents, large-scale gas consumers, were aggrieved because the approved prices resulted in substantial price increases. They sought judicial review of NERSA's Maximum Price Decision and Tariff Decision on grounds of irrationality and unreasonableness under PAJA.