The notions of slavery, servitude, and forced labour, despite having very quickly fallen into abeyance after their conception in the late 1920s and early 1930s, are now once again gaining rapidly in importance. While various instruments set out the definitions of these concepts, there has been very little guidance on their parameters or their normative content. But this problem is greatly alleviated by reference to the legislative history of the provisions as supplementary means of interpretation. The 2012 Bellagio-Harvard Guidelines on the Legal Parameters of Slavery will help shape contemporary debates around slavery as they capture the very essence of what it means to be a slave in a world where ownership of another person is abolished: slavery is about controlling a person in such a manner that they no longer have the liberty to decide their fate. As for servitude, the 1956 Supplementary Convention sets out the various types of servitude established by international law. The conventional servitudes of debt bondage, serfdom, servile marriage, and trafficking in children provide legal certainty where attempts in international human rights law to give content to a stand-alone understanding of ‘servitude’ have thus far failed. Finally, where forced labour is concerned, the claim of its status as a jus cogens norm is difficult to sustain in the context where States continue to use the exceptions inherent in the definition set out in the 1930 Forced Labour Convention. Contemporary debates should leave room to consider whether there is continued justification for the exceptions to forced or compulsory labour in the light of the adoption of the 2014 Protocol to that Convention.