The Biological Weapons Convention at Fifty

[Barry de Vries is a Postdoctoral Research Fellow in the project CBWNet at the Chair for Public Law and International Public Law at Justus-Liebig-University Giessen (Germany) and an Associated Research Fellow at Peace Research Institute Frankfurt.

Kristoffer Burck (PhD candidate) and Sannimari Veini are both Research Assistants at the Chair for Public Law and International Public Law at Justus-Liebig-University Giessen and an Associated Research Fellow at Peace Research Institute Frankfurt.]

This year marks the 50^th anniversary of the entry into force of the Biological Weapons Convention (BWC), formally known as the Convention on the Prohibition of the Development, Production, and Stockpiling of Bacteriological (Biological) and Toxin Weapons. The BWC is one of the most significant arms control agreements of the modern era as it marked the first time an entire category of weapons of mass destruction—biological and toxin weapons—was comprehensively banned. Over the past half-century, the BWC has achieved near-universal acceptance, with 189 states parties and four signatories (Egypt, Haiti, Somalia, and Syria). The longevity of the BWC demonstrates its foundational role in establishing the norm that biological weapons are legally and morally prohibited.

Although the Convention was negotiated during the Cold War, the treaty remains highly relevant in today’s era of rapid scientific breakthroughs, potential dual-use technologies, and shifting geopolitical landscapes. In reflecting on its 50th anniversary, the BWC’s mixed legacy of strengths and weaknesses underscores the continuing need for international cooperation and dedicated efforts to prevent the hostile application of biotechnology. To take stock of the past, present, and future of the BWC, we invited renowned experts on the legal, scientific, and political dimensions of biological weapons to contribute to an Edited Volume commemorating the Convention´s 50^th Anniversary, titled “50 Years of the Biological Weapons Convention: Past, Present and Future.” While the volume will be published later this year and offer in-depth analyses and fresh insights, this blog post provides a preliminary overview of the BWC´s history, including efforts to strengthen the convention, current challenges, and future developments.  

The History of the BWC

Broadly defined, the category of biological weapons includes living organisms or toxins derived from organisms that can cause illness, disability, or death, along with the equipment or means of their delivery. Historical accounts trace their use back centuries, including poisoning wells with toxic substances, catapulting plague-infected corpses over city walls, and infecting enemy populations with diseases such as smallpox. However, the large-scale weaponization of biological agents took place in the 19th and 20th centuries, when major discoveries in microbiology and an increased understanding of infectious diseases allowed for pathogen culturing and manipulation. Paired with ever-improving delivery systems, biological weapons development became a focus area for nations in Europe, Asia, and North America, in a horserace towards militarization. By World War II, many major powers had active biological weapons programs. Notably, Japan used biological warfare in China, infecting civilians with plague and cholera. During the Cold War, both superpowers, as well as some of their affiliated states, continued research into biological agents, raising fears of a new kind of arms race. Apartheid South Africa and Rhodesia maintained active biological weapons programmes with the aim of using these weapons against potential uprisings of their disenfranchised black populations. 

Before the BWC, international norms concerning chemical and biological warfare were shaped primarily by the 1925 Geneva Protocol, which prohibited the use of chemical and bacteriological weapons in war. Although a landmark agreement at the time, the Protocol was limited in scope and enforceability. States could – and often did – maintain reservations that allowed them to retaliate in kind if they were first attacked with such weapons. Moreover, the Protocol did not prohibit the development, production, or stockpiling of chemical or biological agents — only their use in wartime. The Protocol was also interpreted by most states to only bind state behaviour in conflict among High Contracting Parties, leading to the view that the use of biological weapons in non-international armed conflict, including against colonial subjects, would still be permitted. 

During the 1960s, pressure mounted for a stronger international framework. Key developments were the decision to “decouple” negotiations on prohibiting biological weapons from parallel efforts on chemical weapons and the United States’ unilateral declaration in 1969 to end its biological weapons program. By 1972, the process culminated in the signing of the BWC, which entered into force  50 years ago. 

Core Provisions and Structure of the BWC

Article I of the BWC is the heart of the convention, prohibiting states parties from developing, producing, stockpiling, or otherwise acquiring or retaining “microbial or other biological agents, or toxins whatever their origin or method of production, of types and in quantities that have no justification for prophylactic, protective or other peaceful purposes.” The treaty also bans weapons, equipment, and means of delivery designed to use such agents or toxins for hostile purposes. The broad and technologically neutral language — often referred to as the “general purpose criterion”—guarantees that all biological agents and technologies are covered, regardless of scientific advancements. A similar approach was later applied in the Chemical Weapons Convention, which entered into force 22 years later.

One point of note is that the BWC does not explicitly ban the “use” of biological weapons within the main articles. This omission originally reflected the view that the 1925 Geneva Protocol already covered use and, at the time, states were reluctant to create parallel prohibitions. However, subsequent BWC Review Conferences have clarified that using biological weapons would violate Article I, which arguably closed the gap created by the view that the Geneva Protocol only applied in international armed conflicts.

Other key articles mandate the destruction of any existing biological weapons (Article II), prohibit their transfer (Article III), and require states parties to enact national implementation measures (Article IV). Article V encourages consultations to address concerns over treaty implementation, while Article VI allows states to lodge complaints with the UN Security Council if they suspect a breach, a procedure that rose to prominence in the context of Russia´s false allegations of Ukrainian laboratories conducting biological weapons research. Article VII commits states parties to assist one another if exposed to danger as a result of a treaty violation. Article X further underscores the importance of peaceful international cooperation in biotechnology, emphasizing that the BWC should not impede legitimate research and medical progress.

Efforts to Strengthen the Convention

While the BWC was groundbreaking, it also faced immediate criticism for lacking formal verification or compliance mechanisms. Unlike the later Chemical Weapons Convention, the BWC does not require declarations of biological facilities or provide on-site inspections – a deficiency that has repeatedly caused tensions, as verification is essential in determining whether states are genuinely upholding their obligations.

Efforts to strengthen the BWC began with the introduction of Confidence-Building Measures (CBMs) in the 1980s, which encouraged states parties to voluntarily exchange data on high-containment laboratories and vaccine production facilities, as well as other relevant information. However, the CBMs are not legally binding, and many states either fail to submit them or do so inconsistently. In 2024 CBMs were submitted by 112 of (at the time) 187 state parties, continuing a constantly rising trend of submissions from only 78 in 2017. A more comprehensive effort to create a Verification Protocol emerged in the 1990s, led by an Ad-Hoc Group that sought to draft a legally binding instrument to address compliance concerns. Despite intensive negotiations, the initiative collapsed in 2001 when the United States rejected the proposed protocol by reasoning that it would not prevent covert programs and could compromise commercial secrets and national security. While the United States was the state ultimately walking away from the negotiations, other states shared some concerns about the direction of the Protocol, making the failure not just the result of a sole dissenting state. 

The collapse of the Verification Protocol discussions affected the momentum for an enforcement mechanism significantly, but it did lead to the inception of the Implementation Support Unit (ISU) under the United Nations Office for Disarmament Affairs (UNODA) in Geneva. Although small and limited in mandate, the ISU provides crucial administrative and technical support to states parties, facilitating dialogue and assisting with treaty obligations. Its mandate has been repeatedly renewed and role underlined by Review Conference decisions, with the latest in 2022 increasing the ISU´s staff from three to four positions. 

Another positive outcome of the failed Verification Protocol negotiations was the establishment of a series of intersessional meetings between Review Conferences. These gatherings allow states parties, experts, and other stakeholders to discuss specific issues — ranging from scientific developments to strengthening national measures and improving disease surveillance capacities. While primarily consultative, the meetings foster a culture of transparency and cooperation, reinforcing the global norm against biological weapons.

Nevertheless, absent a Verification Protocol, states have to rely on CBMs for trust building and a politicized process through the UN Security Council for conflict resolution. False allegations of non-compliance, such as the most recent ones by Russia against Ukraine, do not lead to independent fact-finding and thus leave room for misuse. Another persistent issue are disagreements over the extent of cooperation required under Article X, with numerous states in the Global South calling on states with a more developed biotechnological industry to cooperate more extensively to ensure that the peaceful use of such technology benefits all nations. 

To fill the persistent gaps, the last Review Conference in 2022 established a dedicated Working Group on strengthening the BWC, which, among other topics, focuses on efforts to prevent the misuse of biological science and technology. The Working Group made considerable progress towards proposals on mechanisms for addressing future developments in Science and Technology and on international cooperation and assistance in line with Article X. However, while the timeline foresaw the ratification of these mechanisms at a special conference later in 2025, Russian disagreement on the last evening of deliberations derailed the consensus-based negotiations.

Looking Ahead

Half a century after its entry into force, the BWC remains a cornerstone of international security. Nevertheless, the rapid acceleration in biotechnology poses both enormous potential benefits and serious risks. Synthetic biology, genetic engineering, and artificial intelligence can revolutionize medicine and industry, yet they also enable malicious actors to develop more potent or targeted biological agents. The dual-use nature of many life science innovations makes regulation and oversight more complicated, forcing policymakers to balance scientific freedom with security concerns. 

Despite its challenges, the BWC has demonstrated resilience. It has near-universal membership, and the taboo against biological weapons is firmly rooted in the international legal landscape. No state party has openly withdrawn from the treaty, indicating broad acceptance of its core prohibitions. Even amidst misinformation campaigns, no state party contests the comprehensive legal and moral taboo against biological weapons. Moreover, the COVID-19 pandemic underscored the devastating potential of biological threats — whether they occur naturally or deliberately — and further highlighted the urgent need for global collaboration on preparedness, early detection, and response.

Renewed discussions on ways to enhance compliance and verification mechanisms suggest that states parties recognize the BWC’s limitations and seek practical improvements. Although achieving consensus on a legally binding verification instrument remains difficult, the fact that these topics are back on the agenda reveals a collective will to address emerging threats. The growing emphasis on misinformation and its impact on biosecurity further indicates the treaty community’s efforts to address the evolving nature of potential threats.

Looking ahead, the BWC’s success will hinge on the international community’s ability to adapt it to rapidly changing technological frontiers, reaffirm its relevance, and develop stronger measures to ensure compliance. The treaty’s near-universal acceptance signals the depth of its normative impact, but effective implementation and transparency remain vital. If member states can harness the momentum from ongoing discussions and intersessional meetings, the BWC will remain a central pillar of arms control, safeguarding humanity from the horrors of biological warfare. Its legacy, spanning half a century, stands as a testament to what can be achieved when nations unite to confront dire threats to global security — and serves as a reminder that vigilance, innovation, and cooperation are essential to preserve those achievements in the face of ever-evolving challenges.