Dual-use refers to a technology, a chemical, or a microorganism that has applications that are legal and peaceful, or illegal and a risk to the public. The term is commonly used in counterproliferation, but also is relevant to fields such as the drug trade, and to equipment and technology with general military applications. It is used by a number of countries and multinational organizations. The European Union uses a fairly broad description that could include conventional weapons or other military devices that are not weapons of mass destruction: "Goods and technologies are considered to be dual-use when they can be used for both civil and military purposes." 
In the past, it primarily has been applied to production, on an industrial scale, of hazardous substances or devices. The term is now also applied to dual use research of concern (DURC) as “research that, based on current understanding, can be reasonably anticipated to provide knowledge, products, or technologies that could be directly misapplied by others.” DURC is of greatest concern with respect to biological weapons, where, of weapons of mass destruction, the smallest production quantities are significant. Radiological weapons also can be involve small quantities.
Especially with respect to life sciences DURC, there is
a tension between freedom of research and national security... As security communities have pushed for tighter oversight of research, scientific communities have been quick to grasp that certain biosecurity regulations, such as export controls or visa controls for foreign scientists, run the risk of being inadvertently disruptive. Members of the US NSABB have even argued that the inhibition of life science research could be considered a threat to national security and public health in and of itself. Yet as concerns the rationale for biosecurity controls, the scientific community has been generally muted. Although this may be related to the secrecy surrounding intelligence about terrorist organizations, classified snippets of information should not have priority over expert technical input. Ceding the debate to the security community could lead to inaccurate threat assessments and the adoption of inappropriate biosecurity control measures.
The Chemical Weapons Convention, for example, has three Schedules of chemicals. Schedule I have few if any uses other than as chemical weapons, although it still may be legitimate for an approved laboratory to have small quantities, for the purpose of developing chemical weapon detectors and defenses. Schedule II have both weapons and non-weapon applications, with enough of a likelihood of weapons applicability that the proposed user must be checked carefully. Schedule III chemicals have substantial industrial applications, but still need to be monitored to be sure they are not diverted into illicit weapons programs.
Under the rules of the U.S. Drug Enforcement Administration, there are two lists of chemicals that have legitimate uses, but also can be used in the manufacture of illicit drugs. Some of the List I compounds are quite specialized and have few applications outside medical research and legal manufacturing, or the production of drugs of abuse. Still, the list contains substances as common as iodine. List II contains chemicals that are used more in industry than in illicit drug manufacturing, such as acetone, hydrochloric acid and sulfuric acid.
In nuclear arms control, it was understood that certain materials could go into a reactor, but it would take inspection of the nuclear reactor to determine if the use was peaceful. Some components, such as the krytron, a switch for precisely timed pulses of electricity, are usually thought to be parts of the implosion system of a nuclear weapon, but also have applications in medical devices such as a lithotripter.
Biological dual-use materials are some of the most difficult to evaluate, since almost all organisms capable of being made into biological weapons also are diseases of humans or animals, and thus legitimate to have in a diagnostic laboratory. The only clear-cut exception would be Variola major, the smallpox virus; smallpox has been eradicated from the wild.
Smallpox virus is one of the organisms, probably of greatest concern, in the Select Agent Program list. DURC is broader than the focus of Select Agent research, which "is a very specific subset of life sciences research; it involves only those microorganisms and toxins specifically identified in DHHS and USDA regulations as having the potential to pose a severe threat to human, animal, or plant health, or to animal and plant products.
"Dual use research is a concept that relates to a broad category of life sciences research. Certain research projects that do or do not involve Select Agents may be considered dual use research depending on the nature of the particular experiments and the potential for misuse of the results and/or technology. Within this smaller category there will be some projects that may be considered dual use research of concern. This latter category is the focus of the NSABB's recommendations to the Federal government. 
- Trade Topics: Dual Use, Trade European Commission
- NSABB frequently asked questions. What is “dual use research” and “dual use research of concern”?, US National Science Advisory Board for Biosecurity (NSABB), Office of Biotechnology Activities, Office of Science Policy, National Institutes of Health, 2010
- Suk JE, Zmorzynska A, Hunger I, Biederbick W, Sasse J, et al. (2011), "Dual-Use Research and Technological Diffusion: Reconsidering the Bioterrorism Threat Spectrum", PLoS Pathog 7 (1): e1001253, DOI:10.1371/journal.ppat.1001253