Loch, A.Croft, M.Giancaspro, M.Adamson, D.2024-05-212024-05-212024nature water, 2024; 2(4):380-3892731-60842731-6084https://hdl.handle.net/2440/140894Analysis of water theft remains challenging given poor data and limited cases, restricting assessments to higher levels where attempted. However, high-level research within key transboundary contexts can offer evidence for improved theft deterrence and critical legislative change requirements, along with institutional insights for other jurisdictions. For example, Federal water regulators of Australia’s Murray–Darling Basin (MDB), which is an important transboundary water system, have called for consistency in compliance and certainty across State jurisdictions to help protect water market confidence and resource reallocation outcomes that are critical in drought periods. Here we explore the complex legal processes for penalty setting in water theft cases that may drive ineffective compliance when the value of legal harm is procedurally downgraded under the legitimate consideration of mitigating factors. We aim to identify applied certainty and severity deterrence principles for reducing environmental and economic harm, as well as how to incorporate alternate water values in penalty setting to inform a future framework to analyse MDB legislative consistency and institutional transparency with lessons for other countries. This paper explores legal processes for penalty setting in water theft cases in transboundary water systems and develops ideas to identify differences and potentially drive consistency between jurisdictions.en© The Author(s), under exclusive licence to Springer Nature Limited 2024. Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.water theft; Murray–Darling Basin; legal review; detection; deterrence; penaltiesJournal article10.1038/s44221-024-00223-82024-02-19685339Loch, A. [0000-0002-1436-8768]Croft, M. [0009-0001-9944-5880]Giancaspro, M. [0000-0002-0121-0590]Adamson, D. [0000-0003-1616-968X]