The previous essays reveal wide disagreement about the concepts needed to analyse coerced labor. 2 Contemporary Brazilian legislation regards as “modern slavery” what others would regard as “forced labor.” 3 Since very early on the definitions of slavery and other forms of coerced labor adopted by international organizations have been at odds with one another. The confusion dates from the 1920s at the latest. Article 1 of the League of Nations Slavery Convention of 1926 defined slavery in legal terms:“the status or condition of a person over whom any or all of the powers attaching to the right of ownership are exercised.” Article 2.1 of the International Labor Organization’s Convention Concerning Forced or Compulsory Labour of 1930 (No. 29), however, does not presume the existence of a legal basis: indeed,“all work or service that is exacted from any person under the menace of any penalty and for which the said person has not offered himself or herself voluntarily” is regarded as forced or compulsory labor. 4

Not only have the standard definitions been inconsistent for so long, they are generally vague. That vagueness began already with the League of Nations. What does it mean when the League of Nations talks about “any or all of the powers attaching to the right of ownership”? Modern legal theory distinguishes at least eleven such “powers,” including the duty to prevent harmful use. 5 The Geneva Convention of 14 December 1956 refers to “Slavery, the Slave