Although negotiated and adopted through international law mechanisms, the legal instruments mentioned under Key issues differ from traditional public international law (PIL) instruments as they mainly relate to so-called transnational law. Unlike PIL, which is principally concerned with States and with regulating the conduct of States and international organizations, and their relations inter se, and with some other persons, transnational law concerns a broader spectrum of subjects, including States, international organizations, governments, multinational and national companies, natural and legal persons that perform activities or have influences across states lines (American Law Institute, 1987). These areas and activities are normally regulated by domestic law, and usually cross borders or have an implication or impact that transcends national boundaries. Firearms trafficking, for example, or the international trade in firearms, are by their nature a typical transnational activity whose regulation would be subject to a variety of laws that, in this context, can be correctly described as transnational law.
In addition, the international instruments concerned with preventing and combating the illicit trafficking and the illegal trade in firearms form part of this category of transnational law instruments, as they address different domains of national laws (constitutional, civil, administrative, commercial, criminal etc.) with transnational implications. Consequently, the instruments that deal specifically with the criminal justice aspects of the firearms control regime fall under the sub-category of transnational criminal law.
The distinction between international criminal law and transnational criminal law is not always very clear. International criminal law stricto sensu is referred to the branch of international public law that defines and covers typically the so-called core crimes, such as genocide, war crimes, crimes against humanity and aggression; whereas transnational criminal law covers 'crimes of international concern' or so-called treaty crimes. The latter are set out basically in treaties (see for example, the criminal offences established under UNTOC and its Protocols) as crimes for which suspects are to be prosecuted only through domestic penal mechanisms in the State where they were arrested or are to be extradited to the State in which prosecution will take place.
Bassiouni (2003) considers the distinction between international criminal law and transnational criminal law. He starts from the observation that international criminal law is the product of the convergence of two different legal disciplines which have emerged and developed along different paths so as to be complementary, but co-extensive and separate (Bassiouni, 2003). These two disciplines are the criminal aspects of international law and the international aspects of national criminal law.
The criminal aspects of international law consist of a body of international proscriptions which criminalize certain types of conduct irrespective of particular enforcement modalities and mechanisms, such as: aggression, war crimes, unlawful use of weapons, crimes against humanity, genocide, apartheid, slavery and slave-related practices, torture, unlawful medical experimentation, piracy, hijacking, kidnapping of diplomats, taking of civilian hostages, drug offenses, falsification and counterfeiting, theft of archaeological and national treasures, bribery of public officials, interference with submarine cables, and international traffic in obscene publications. For Bassiouni, although some of these crimes emerge from customary international law, they are also included in one form or another in conventional international criminal law.
On the other hand, Boister (2003) insists on the distinction between core international crimes covered by international criminal law stricto sensu on the one hand, and treaty crimes on the other. He argues in favour of labelling the latter category as 'transnational criminal law'. In his view, by adopting the Rome Statute of the International Criminal Code with jurisdiction over core crimes, the international community has focused public attention on these crimes, but has in a way underestimated the significance of analysing in a coherent manner the system of law that the crime control treaties establish. A ﬁrst step in focusing attention on this system would be to give it an easily identiﬁable label - 'transnational criminal law'. Examples of transnational crime treaties establishing transnational criminal law offences, or treaty crimes, are inter alia: the United Nations Convention against Illicit Traffic in Narcotic Drugs and Psychotropic Substances of 1988; the 2000 United Natons Convention against Transnational Organized Crime (UNTOC) and its three supplementary Protocols on Human Trafficking, Migrant Smuggling and Firearms Trafficking; and the 2003 United Nations Convention against Corruption (UNCAC). Module 5 will address primarily UNTOC and the Firearms Protocol. For additional information on the Protocols on Human Trafficking and Migrant Smuggling, please see the UNODC Teaching Module Series on Trafficking in Persons and Smuggling of Migrants; information on the UNCAC and corruption in general can be found in the Module Series on Anti-Corruption.