In January 1946, the United Kingdom, Soviet Union, United States, France, China, and Canada resolved that one of the first tasks for an embryonic United Nations was to establish a commission to “deal with the problems raised by the discovery of atomic energy.” But already, they were running behind. The United States had bombed Hiroshima and Nagasaki, and many countries were loath to legally forgo the possibility of building nuclear weapons. After decades of negotiation, diplomatic agreements like the Partial Nuclear Test Ban Treaty (1963) and the Nuclear Non-Proliferation Treaty (1970) have limited nuclear proliferation—but not prevented it entirely.
Today, biology evokes another novel threat to peace and security: the potential to create mirror bacteria. Mirror bacteria are living, replicating, synthetic organisms composed of biomolecules that are the structural mirror images of their natural counterparts. Physical differences in structure affect how these molecules bend light and how they behave chemically. Just like right and left hands, mirror image versions of molecules are nonsuperimposable. They may look the same when reflected in a mirror, but their interactions with other molecules and the biosphere would be very different, in the same way that a right hand cannot properly shake a left hand.
According to recent analyses, mirror bacteria could present two main dangers. First, they could evade the immune systems of many living things because they would not be properly recognized and controlled, causing pandemics that could kill people and animals and devastate crops. Second, mirror bacteria could evade predators that keep populations of natural bacteria in check, facilitating their global spread and potentially leading to disruptions to food chains, mass extinctions, and ecosystem collapse. Efforts at containment and potential countermeasures would likely fail to prevent their spread.
But in addressing the risks of mirror bacteria, we need not reprise the story of nuclear weapons, for two reasons. First, the material threat has not yet emerged. Whereas nuclear weapons technology was already available and in use as experts sounded the alarm about risks, no scientist has created mirror bacteria, and the world is likely at least ten years away from their creation. But with focus, resources, and technical innovation, the timeline may well be shorter. Second, the risks clearly significantly outweigh the potential benefits. Possession of nuclear weapons afforded countries strategic advantage, and early in the nuclear age, some believed nuclear explosives could have meaningful nonmilitary benefits for large-scale excavation. Mirror bacteria, by most accounts, appear to lack substantial potential benefits.
Emerging scientific consensus about the risks from mirror life presents a rare and promising policy opportunity to prevent the emergence of a global threat. Indeed, leading scientists around the world, including in China, the United States, and Europe, now agree that mirror bacteria should not be created—among them several who previously pursued this goal. In December 2024, thirty-eight prominent scientists warned about the risks and urged researchers, policymakers, funders, industry, and civil society to develop appropriate governance and safeguards. A 2025 independent examination of the 2024 analysis by the German Central Committee on Biological Safety supported its key findings. At subsequent meetings in Asilomar, California, and the Institut Pasteur in Paris, the need to develop appropriate governance and safeguards has found additional support from hundreds of scientists, ethicists, security experts, policymakers, and others.
Despite growing international agreement among scientists, there is more work to be done to catalyze action and secure policy commitments. To that end, researchers at the Carnegie Endowment for International Peace hosted a convening to bridge scientific and policy communities. We brought together experts from academia, international organizations, think tanks, and industry, eliciting a wide range of perspectives on how to exercise anticipatory governance to prevent the creation of mirror life.
Recommendations
Managing the risks of mirror life—and accommodating scientific uncertainty and the understandable interest in further scientific progress—requires pursuing policy measures that operate on multiple timescales. In the medium term, negotiating an international code of conduct and voluntary commitments by scientists and funders to not create mirror bacteria could pave the way toward stronger actions from governments to ensure that mirror bacteria cannot be created. National and/or international regulation of key enabling technologies will necessitate greater discussion about which technologies should be controlled and how.
To lay the foundation for these efforts, the discussion at Carnegie surfaced three near-term recommendations.
First, the global scientific community should clearly and accurately communicate the risks of mirror bacteria to the public, policymakers, and other key stakeholders.
Mirror bacteria pose risks unlike any previously studied biological threat: They could cause broad, irreversible, and concurrent harm to humans, animals, crops and other plants, and entire ecosystems. Scientists worldwide have a duty to explain these risks clearly and accurately while being transparent about the limits of current knowledge. Clear understanding among the public, policymakers, and other stakeholders enables constructive action, and proactive communication from scientists strengthens trust in science as an ethical enterprise.
Scientists should be prepared to explain the nuances of mirror bacteria and to address potential misconceptions. For example, based on current understandings, the clearest potential benefit of developing mirror bacteria would be to use them as a platform to synthesize certain specialized mirror biomolecules that may have value as therapeutics. Yet mirror biomolecules can already be made through conventional chemical synthesis. Mirror biology research constitutes a tiny fraction of the larger field of synthetic biology. It appears possible to prevent the development of mirror bacteria without unduly hindering potentially beneficial work on mirror biomolecules or blocking important advances in synthetic biology.
Second, public and private funders should commit to not funding research with the goal of creating mirror bacteria.
At present, we do not know of any researchers pursuing the creation of mirror bacteria. Estimates suggest that it may take more than ten years for scientists to overcome the significant technical hurdles to making them. But with a concerted effort (potentially assisted by further developments in artificial intelligence) and investments of $500 million to $1 billion, this timeline might be accelerated. To ensure funding is not directed toward making mirror life, public and private funders should commit to not funding research with the goal of creating mirror life. To be effective, such commitments would need to be endorsed by as many agencies and organizations as possible—with particular attention to the largest ones—lest researchers simply find a different, willing funder.
Third, policymakers should engage with diverse stakeholders in the process of establishing red lines and other policies to robustly ensure that mirror bacteria are not created.
Although commitments from funders are an important first step, new policies will ultimately be needed to ensure that mirror bacteria are not created. To be effective, policies should draw clear red lines around research that could advance the creation of mirror bacteria while preserving scientific freedom and the benefits of research as much as possible. These red lines are not yet clear; scientists convened in Manchester, United Kingdom, in September 2025 to continue discussions on where they might be drawn. Policymakers should seek input from the synthetic biology community early and often.
At the same time, some scientists may hold vested interests in preserving their own lines of research, even if that research would enable the creation of mirror bacteria. Crucially, scientists are not the only relevant stakeholders. Policymakers must also seek input from civil society groups, ethicists, industry groups, experts from international organizations, and others to ensure that any potential policies are aligned with the goals and values of society as a whole.
Conclusion
We should start to guard against the creation of mirror bacteria now. The risks are too serious to wait, and the costs of action are small. Although ten years may seem a long way off, building international consensus on technical regulation takes time. We also must acknowledge that progress toward mirror bacteria may happen more quickly than expected; history is littered with examples of technological development outpacing estimates.
Scientists, policymakers, philanthropists, civil society groups, and investors all have a role to play in ensuring that mirror bacteria are not made. Unlike the nuclear negotiators of the twentieth century, these groups have the opportunity to establish governance frameworks before a threatening capability exists, rather than attempting to control its spread afterward. The scientific community is coalescing around the view that this technology should not be pursued. Policymakers must ensure that it cannot be.
