The development of the Entobunsui circular water divider in early 20th-century Japan can be seen as a way of stabilising usufructuary rights through technological design. A common characteristic of a right of usufruct is use of and benefit from a resource without wasting it. In agrarian societies, irrigation water is typically not owned outright by individuals but shared among communities, with each farmer holding a right to use a portion for cultivation. It is the norm not to waste water. As well water supply can be variable, is rivalrous (one person’s use reduces what is available), and may be difficult to measure without flow meters, gauges and monitoring systems. This makes equitable allocation both legally and practically complex.
Prior to the Entobunsui, water distribution relied on split channels, which assumed that dividing physical pathways would produce equal outcomes. In reality, differences in flow speed, sedimentation, and channel manipulation meant that upstream users could capture more than their share. This undermined the normative structure of use or usufructuary rights, where fairness depends on proportional access rather than physical possession. The result was persistent conflict, as legal or customary entitlements could not be reliably enforced through existing infrastructure.
Embedding rules into infrastructure
The Entobunsui addressed the problem of disputes and conflicts by embedding proportional allocation directly into the hydraulic system — the infrastructure. Its circular design ensured that water was distributed according to predetermined ratios, regardless of fluctuations in flow. In effect, it transformed an abstract legal entitlement into a physically enforced outcome. This is significant from a legal perspective: instead of relying on ex post dispute resolution or social enforcement, the system operationalised rights ex ante. Each user’s right was no longer dependent on trust or vigilance, but on the structure of the device itself.
In effect, this innovation can be understood as an early analogue to modern digital “smart contracts”. Just as code can automate compliance with agreed terms, the Entobunsui automated compliance with water-sharing norms. However, unlike purely digital systems, it remained grounded in communal governance: the ratios embedded in the device still reflected negotiated social agreements.
What the Entobunsui demonstrates is that usufructuary rights are most effective when aligned with enforceable mechanisms that reflect the physical realities of the resource. By harmonising legal entitlement with material distribution, it reduced incentives for opportunism and transformed a source of conflict into a stable, shared system of use. Crucially, it shows that where legal rights depend on variable and rival resources, embedding enforcement directly into the infrastructure can substitute for imperfect monitoring and dispute resolution, thereby enhancing both fairness and reliability.
Controls to scale
The Entobunsui can also be understood as an early form of “control to scale”. Generally, human cooperation beyond small groups depends on systems that standardise behaviour and reduce the need for constant negotiation. Thus, developed traditional control mechanisms, i.e. rules, records, oversight, to enable large-scale coordination. But these were often slow, contestable and reliant on human enforcement.
In the context of irrigation, this meant ongoing monitoring and disputes over compliance. The Entobunsui replaced these record-keeping or “paper-era” controls with a self-executing physical protocol, allowing many users to rely on a shared system without continuous supervision. In doing so, it is akin to the role of smart contracts in the digital economy, that is, embedding rules into infrastructure so that coordination scales efficiently.
However, just as with modern smart contracts, such controls do not eliminate the need for governance. What happens is they shift governance upstream into the design of the system itself, where decisions about allocation, fairness and also adaptability must be made by some collective body. This reallocation of governance concentrates power in designers and rule-setters (a collective body), but it still requires transparency, a degree of contestability, and periodic review to prevent rigid or unjust outcomes from being locked into the system.
Onwards to programmable relationships
Useful insights can be gained by contrasting traditional “paper-era” controls with the possibilities of smart contracts. Paper-based systems are typically static, standardised and mediated through hierarchical authorisations, with limited confidentiality and little capacity for dynamic interaction. Even electronic data interchange (EDI) in trade largely replicated these structures, digitising forms without transforming the underlying relationships.
By contrast, smart contracts enable interactive, granular and context-responsive protocols that can more closely mirror the actual performance of obligations expected by parties. In this sense, the Entobunsui can be seen as a precursor of today’s smart contracts. It did not merely document water rights or rely on managerial allocation, but embedded the relationship directly into the operational environment, allowing continuous, automatic, and proportionate performance.
Modern smart contracts extend this logic beyond physical infrastructure, enabling complex, multi-party relationships to be executed through code rather than paperwork. This shift still raises legal questions though, in that as contractual performance becomes embedded in systems rather than expressed in documents, the challenge is ensuring that flexibility, confidentiality and accountability do exist. These are often mediated through human judgment in paper/analogue systems, so they are not lost but reconstituted within these new digital programmable frameworks. The smart contract environment may still need to refer to humans when matters get too complex.
https://substack.com/@macropsychic/note/c-229034629
