From Pope Benedict XVI’s encyclical Caritas in Veritate (2009):
Another aspect of integral human development that is worthy of attention is the phenomenon of migration. This is a striking phenomenon because of the sheer numbers of people involved, the social, economic, political, cultural and religious problems it raises, and the dramatic challenges it poses to nations and the international community. We can say that we are facing a social phenomenon of epoch-making proportions that requires bold, forward-looking policies of international cooperation if it is to be handled effectively. Such policies should set out from close collaboration between the migrants’ countries of origin and their countries of destination; it should be accompanied by adequate international norms able to coordinate different legislative systems with a view to safeguarding the needs and rights of individual migrants and their families, and at the same time, those of the host countries. No country can be expected to address today’s problems of migration by itself. We are all witnesses of the burden of suffering, the dislocation and the aspirations that accompany the flow of migrants. The phenomenon, as everyone knows, is difficult to manage; but there is no doubt that foreign workers, despite any difficulties concerning integration, make a significant contribution to the economic development of the host country through their labour, besides that which they make to their country of origin through the money they send home. Obviously, these labourers cannot be considered as a commodity or a mere workforce. They must not, therefore, be treated like any other factor of production. Every migrant is a human person who, as such, possesses fundamental, inalienable rights that must be respected by everyone and in every circumstance.142
142 Cf. Pontifical Council for the Pastoral Care of Migrants and Itinerant People, Instruction Erga Migrantes Caritas Christi (3 May 2004): Acta Apostolicæ Sedis 96 (2004), 762-822.
— Caritas in Veritate 62