How should the strategies and regulations of the Mexican laws be designed in order to trigger a country to go from a non-sustainable energy economy towards a sustainable energy economy? This paper proposes a classroom debate of the reformed Law of Public Electricity Service in Mexico (LSPEE, 1992: Ley del Servicio Publico de Energia Electrica), which, in 1992, opened new opportunities for private investment in the Mexican utility industry. The legal reforms allow the private sector to invest, operate, and be owners of part of the public utility system in Mexico, mainly, for power generation. Evaluating the dilemmas of the past, students are encouraged to debate present and future reforms considering political, economic and financial frameworks with a sustainable development approach and to evaluate the role of foreign and private investment in public utilities around the world.