Many concepts sound great in theory but become thorny in practice. One of those concepts is the idea of the "public interest". The term has existed as a principle for good government, in various forms, for thousands of years and it's widely used in law. In a recent blog post, a well-known Ethereum developer implicitly put forward the idea that public blockchains ought to be run in the "public interest". But what does the term mean and is that a standard that ought to be at the heart of Ethereum, or any other public blockchain? It's a concept that's widely used in law. Why not for Ethereum?

The term "public interest" appears in ethical guides, statutes, and administrative law textbooks all over the world. But this simple term hides a complicated reality. Few people agree on what the "public interest" is, how to identfiy it, or how to know when something isn't in the public interest. This is a standard that opens the door to debate, rather than providing a standard in the sense of Ethereum's ERC-20, technical standards, or really anything that programmers would say is a "standard". What lawyers and regulators call a "standard" might surprise people who are not familiar with the thousands of pages of scholarship on various sorts of "standards" in law (e.g. Canadian administrative law).

Journalists debate what sort of coverage is "in the public interest". Lawyers and lawmakers throughtout the Commonwealth have attempted to develop analytical frameworks to understand how it ought to be applied to understanding laws (for example, in Australia). In Canada there are thousands of statutes that mention the term "public interest". In the United States, the "public interest" has been debated for decades in the context of Federal regulation of communications. Despite enormous amounts of work by smart people around the world there's little agreement on the precise meaning of the term (and that may a desirable feature to those who draft statutes).

The "public interest" can be hard to identify or interpret in the context of a single jurisdiction with a small number of players. Lawyers and academics have debated the term, in many contexts, for decades, with no end in sight. The idea of public blockchains identifying the "global public interest" (in Vlad's words) seems like an even more intractable task.

But is it necessary? Should blockchains have the "public interest" in mind as the goal? Isn't it sufficient to have a small number of people's interests in mind and then see if it's useful for others? At the very least, if the "public interest" will be the standard for the development of a blockchain then that term ought to be carefully unpacked in order to avoid the danger of the public interest meaning whatever interest a particular member of the public has in mind.