This chapter demonstrates the substantive approach to syari'ah, as opposed to the formal approach. The substantive approach advocates an emancipated understanding of the syari’ah, stressing its original meaning as a ‘path’ or guide, rather than a detailed legal code. The proponents of syari’ah often believed that, as a majority group, their rights and freedoms had been overlooked in the 1945 Constitution. The chapter focuses on the dispute over the meaning of the phrase dengan kewajiban menjalankan Syariat Islam bagi pemeluknya’, and is centred on crucial interpretive questions surrounding the Islamisation of the sources of Indonesian law. It examines some objections to the proposal to include syari’ah in Article 29, such as the belief that the full implementation of formal syari’ah will lead to the establishment of an Islamic state, possibly creating inequality amongst Indonesian citizens. Indonesia is neither a secular nor an Islamic state. It is essential to note that this position is compatible with the substantive syari’ah approach.