Section 4(1)(a) of the Human Trafficking and Exploitation (Scotland) Act 2015 states that it is an offence for any person to hold another person in servitude or slavery. In February 2018, John Miller and Robert McPhee appeared at the High Court in Glasgow, charged on indictment with this offence. In defining both ‘servitude’ and ‘slavery’, the court was obliged, per s 4(2) of the 2015 Act, to have due regard to the understanding of these terms which has evolved out of the jurisprudence of Article 4 of the European Convention on Human Rights (ECHR). ‘Slavery’, then, was said to denote ‘the status or condition of a person over whom any or all of the powers attaching to the rights of ownership are exercised’. If, however, the definition of ‘slavery’ necessarily ‘involves rights of ownership’, then it follows that any enactment of law specifically proscribing slavery is nugatory. Indeed, in Miller, the court ultimately held that ‘there was no evidence upon which they could hold that the complainer had been held in a state of slavery’. This paper consequently asks whether or not in passing s 4(1)(a) of the 2015 Act, Parliament criminalised an impossible action.