A person may move from one country to another or within one country in many different ways, both legal and illegal. It is important to distinguish trafficking from illegal migration or alien smuggling. Although trafficking can include some of the components of illegal migration and alien smuggling—traffickers may, for example, smuggle their victims across borders—questions of consent and coercion separate trafficking from these other illegal activities. As the Special Rapporteur for Violence Against Women noted in her 2000 Report:

It is the non-consensual nature of trafficking that distinguishes it from other forms of migration. The lack of informed consent must not be confused with the illegality of certain forms of migration. While all trafficking is, or should be illegal, all illegal migration is not trafficking. It is important to refrain from telescoping together the concepts of trafficking and illegal migration. At the heart of this distinction is the issue of consent.

Issues of consent and coercion are at the core of the definition of trafficking contained in the UN Protocol to Prevent, Suppress and Punish Trafficking in Persons, Especially Women and Children: "The consent of a victim of trafficking in persons to the intended exploitation . . . shall be irrelevant" where the victim has been subject to force or coercion. As the Special Rapporteur noted in her 2000 Report, it is the use of coercion both during transport and upon arrival in the destination country that distinguishes trafficking from other illegal activities:

Although numerous separate abuses are committed during the course of trafficking, which themselves violate both national and international law, it is the combination of the coerced transport and the coerced end practice that makes trafficking a distinct violation from its component parts. Without this linkage, trafficking would be legally indistinguishable from the individual activities of smuggling and forced labour or slavery-like practices, when in fact trafficking does differ substantively from its component parts. The transport of trafficked persons is inextricably linked to the end purpose of trafficking. Recruitment and transport in the trafficking context is undertaken with the intent to subject the victim of the coerced transport to additional violations in the form of forced labour or slavery-like practices.

European Union documents also make a point of distinguishing smuggling from trafficking. A 2002 European Union Proposal for a Comprehensive Plan to Combat Illegal Immigration and Trafficking of Human Beings in the European Union notes: "The expressions 'smuggling' and 'trafficking' are often used synonymously, although a clear distinction should be drawn as they are substantially different." Referring to definitions contained in the U.N. Convention Against Transnational Organized Crime and its accompanying Protocols, the Proposal continues:

These definitions make it clear that smuggling means helping with an illegal border crossing and illegal entry. Smuggling, therefore, always has a transnational element. This is not necessarily the case with trafficking, where the key element is the exploitative purpose. Trafficking involves the intent to exploit a person, in principle irrespective of how the victim comes to the location where the exploitation takes place. This can involve, in cases where borders are crossed, legal as well as illegal entry into the country of destination. Illegal immigration can also include trafficking aspects, but has indeed a wider scope and relates more to the general illegal entry and residence of persons.

Although trafficking is distinct from migration, it is important for advocates and law enforcement to understand the interplay between these phenomena. Those who wish to migrate, as well as recent migrants, may be particularly vulnerable to traffickers. A voluntary migrant who places herself in the hands of smugglers has put herself into a situation of dependency on the smuggler, and may subsequently become a victim of trafficking. For this reason, it is particularly important that border personnel are trained to recognize the indicators of trafficking. Such training will help border guards in identifying and assisting trafficking victims. It is particularly important that national and international law reflect the distinction between illegal migration and trafficking. The Special Rapporteur is "concerned that many Governments equate illegal migration, particularly illegal migration for prostitution, with trafficking in women." This creates an obstacle for women who might want to seek legal protection from trafficking: Victims of trafficking may be unwilling to contact local authorities because they fear prosecution and/or deportation. More information on legal protections for victims of trafficking is available in the Legal Protection and Protection, Support and Assistance of Victims sections.