Metrorail and the SA Rail Commuters Corporation, as organs of state exercising public power and providing subsidized rail commuter services under the SATS Act, bear a positive public law obligation (arising from sections 15(1) and 23(1) of the SATS Act read with sections 7(2), 10, 11, and 12 of the Constitution) to ensure that reasonable measures are in place to provide for the security of rail commuters. This obligation is informed by the constitutional value of accountability, the nature of the monopoly service, the vulnerability of commuters, and the socio-economic context (serving mainly poor communities with limited alternatives due to apartheid spatial planning). The obligation is not negated by the primary policing responsibility of the SAPS under section 205 of the Constitution; where a "void" exists in policing, Metrorail's complementary role requires it to take reasonable steps. Reasonableness is assessed contextually, considering the nature of the duty, social and economic context, relevant factors, closeness to core activities, threats to fundamental rights, intensity of harm, and resource constraints (which must be substantiated, not merely asserted). The Constitutional Court has jurisdiction to determine factual disputes that constitute "issues connected with decisions on constitutional matters" under section 167(3)(b), and is not bound by the SCA's application of the Plascon-Evans rule where constitutional rights are engaged. Declaratory relief is an appropriate and flexible constitutional remedy that promotes accountability and allows the executive to determine implementation.