In 2007 the Indonesian government cited the United Nations’ Convention on Biological Diversity (CBD) when it claimed sovereignty over influenza viruses isolated from within its territory, denying the World Health Organization (WHO) access to physical samples of H5N1 influenza virus. In response, WHO Member States adopted the Pandemic Influenza Preparedness Framework (PIP Framework) for the sharing of influenza viruses with human pandemic potential. This ended the political stalemate between Indonesia and the WHO, but the international community never addressed the broader legal issue at the core of Indonesia’s claim: do countries have sovereign authority over viruses isolated from within their territories? Answering this question is the starting point of this thesis and is crucial to creating legal certainty for international virus sharing and defending global health security. Genetic resources were largely treated as global public goods under international law until the entry into force of the CBD in 1993. This binding and widely-adopted convention situates genetic resources within the sovereign domain of the Nation State, allowing national governments to regulate access to genetic resources pursuant to their own environmental policies. The domestic laws and policies implemented in the wake of the CBD have created a diverse and complicated regime for accessing genetic resources and sharing benefits associated with their utilisation, referred to as ‘access and benefit-sharing’ (ABS). Until the present research, it has not been clear how these rules apply to viruses outside the narrow remit of pandemic influenza viruses under the PIP Framework. Virus samples are essential for ecological, agricultural and medical research and are vital inputs for the production of vaccines and antivirals. Most viruses are still accessed freely from the environment and shared informally between networks of scientific colleagues without regard to the domestic ABS policies of originating Nation States. This is starting to change as States begin to restrict access to virus samples to exchange them for monetary or non-monetary benefits. This trend is likely to impact scientific research and the development of novel biotechnologies, but it has the most disturbing consequences in the field of public health, where international negotiations over access to pathogenic virus samples can delay outbreak response efforts. This research examines the legalities of claiming sovereignty over viruses under international law and represents the first systematic effort to situate viruses within the international ABS regime. This research aims to: (1) clarify the status of viruses under international ABS law, (2) examine the facets of the international ABS regime that will shape future virus sharing practices, and (3) determine the impact of virus ABS on virological research. It draws together the key themes of law, scientific research and viruses. The legal question originally posed by Indonesia in 2007 and restated here as the first aim of this research is addressed by means of a textual analysis of the CBD and its Nagoya Protocol. Chapter 2 (published in the European Intellectual Property Review) demonstrates that all viruses are unequivocally ‘genetic resources’ within the remit of these international instruments. This finding clarifies the previously ambiguous status of all viruses as sovereign genetic resources under international law and forms the theoretical basis for the preponderance of this research. In effect, influenza viruses with human pandemic potential are regulated by the PIP Framework and all other viruses are subject to regulation under the CBD and Nagoya Protocol. Four chapters of this thesis address the second aim of this research, examining the facets of the current international ABS regime that will shape future virus sharing arrangements. Chapter 3 (published in the Journal of Law and Medicine) analyses temporality and the conceivable extension of sovereign rights to virus isolates collected before the entry into force of the CBD on 29 December 1993, using the ex situ repositories of smallpox virus held by the United States of America and the Russian Federation as a case study. Chapters 4 and 5 (published in the Journal of Law and Medicine and the Journal of World Intellectual Property respectively) are the first published papers to examine how provisions of the CBD and Nagoya Protocol relating to ‘traditional knowledge associated with genetic resources’ apply to viruses. These chapters provide proof of principle that Indigenous Peoples and Local Communities could possess virus-associated traditional knowledge that can be subject to benefit-sharing obligations. Chapter 6 (published in The Milbank Quarterly) critiques the ABS provisions of the PIP Framework as the only international virus-specific de facto ABS instrument. The Nagoya Protocol creates the flexibility to adopt specialised instruments outside of the default bilateral ABS system created by the CBD and Nagoya Protocol. Chapter 6 demonstrates that while the PIP Framework may be considered a multilateral ABS agreement, it secures just the access side of the ABS ‘grand bargain’ enshrined by the CBD. Chapter 6 cautions against the current proposals to expand the scope of the PIP Framework to include other pathogens. Chapter 7 (published in the Journal of Science Policy and Governance) addresses the third aim of this research by examining how ABS measures have impacted scientific research in the biological disciplines. It shows how domestic legislative, administrative and policy measures implementing the CBD and Nagoya Protocol create legal barriers to accessing genetic resources for biological research and can limit scientific innovation. It demonstrates that ABS policies will have a cooling effect on biotechnological research utilising viral genetic resources if countries start to impose similar legal barriers to accessing virus samples. Chapter 8 concludes that the international ABS regime already fetters virus sharing with unforeseen adverse impacts on global health security. Scientists require access to virus samples for research and development, and timely access to viruses that can cause diseases in humans, plants and animals is critical. As countries start to exercise their sovereign authority over viruses and restrict access to virus samples in order to influence benefit-sharing negotiations, it is ever more important that the international community comprehends the form and structure of virus ABS. This thesis fills the literature void as the first published research to explore the legal and practical issues of accessing virus samples and sharing the benefits associated with their use under the CBD and Nagoya Protocol. Given the deficiencies of the current ABS regime, this research forms the basis for an international debate about alternative models for regulating access to viruses and sharing the associated benefits. During public health emergencies, legal ambiguities around who can control access to viruses and at what price can delay the public health response and ultimately cost lives.