Most of the neo-colonial nation-states in South America, Africa and Asia have historically remained multilingual. Particularly, subcontinent, being the part of Indus Civilization, successfully maintained the legacy of religious and cultural diversity. Pre-colonial lingo-cultural diversity in subcontinent was discouraged and displaced by new linguistic hierarchy during colonial times. In the milieu of WW-II and national liberation movements throughout the world, classical colonial structure was largely weakened at global level and paved the way for internal colonialism. Political leadership of newly formed multiethnic states principally preferred to govern their people as colonial subjects rather than free citizens. European model of 'one language, one culture and one state' has hitherto resulted in many ethno-linguistic movements in different neo-colonial states. Neo-colonial forms of knowledge, categories and instruments of oppression; particularly language policy; is still prevailing in such (in)dependent states where Pakistan is not an exception. Since 1947, language policy in Pakistan has been mainly shaped by and still continues to be overshadowed by its colonial past. This article critically investigates promise(s) and practice(s) of national language policy and the status of linguistic human rights of minorities in education in Lyari, Karachi, Pakistan. The data was collected from various (inter)national public policy documents/declarations along with semi-structured interviews from four different groups of participants i.e. academics, cultural activists, teachers and parents. Findings reveal two diametrically opposed orientations in terms of the use of mother tongue in classroom. School teachers stridently advocated assimilationist language ideology and viewed multilingualism in classroom as a problem to be solved, whereas, cultural activists and academics consider the same as a cultural resource to be properly utilized and the right of the child to be respected. Parents' views are also considered in order to explore the tension between the language of schooling and the language of early socialization of children at home. Moreover, Language Rights model is applied in order to explore (re)production of linguistic injustice through language policy in education.