Longstanding negotiations on the status of marine genetic resources beyond national jurisdiction under a new UN treaty oscillated between the common heritage of mankind and the freedom of the high seas. The final text of the new Biodiversity Beyond National Jurisdiction (BBNJ) Treaty bridges the normative dissonance by crafting a freedom of marine scientific research juxtaposed with the common heritage of humankind. This article argues that the principle is a specific carve‐out from the freedom of scientific research in the United Nations Convention on the Law of the Sea (UNCLOS), enumerated as one of the freedoms of the high seas. The principle of freedom of marine scientific research is best conceived as a property‐protected activity tethered to marine genetic resources where the scope and consequences of the activity demarcate the commons resource. It derives legitimacy and content from the common heritage regimes in UNCLOS as well as the operative elements of Part II of the BBNJ Treaty that address the equitable use of marine genetic resources and digital sequence information on marine genetic resources. As such, this element in the Treaty and the explanation set out here introduces a new and unprecedented constitutionalising norm in global biodiversity governance.