AbstractThe supposed disruptive and transformational potential of blockchain technology has received widespread attention in the media, from legislators, and from academics across disciplines. While much of this attention has revolved around cryptocurrencies such as Bitcoin, many see the true promise of blockchain technology in its potential use for transactions in traditional assets, as well as for facilitating self‐executing ‘smart contracts’, which replace vague and imprecise natural language with unambiguous computer code. This article presents a simple legal argument against the feasibility of a meaningful blockchain‐based economic system. Blockchain‐based systems are shown to be unsuitable for transactions in traditional assets, unless design choices are made which render the use of the technology pointless. The same argument is shown to apply to smart contracts. Legal and practical obstacles therefore mean that, outside its original realm of cryptocurrencies, blockchain technology is highly unlikely to transform economic interactions in the real world.