The state of research into irregular migration has improved in recent years, thanks above all to a large number of smaller studies. However, there are still considerable gaps. Nevertheless, it is possible to derive the following key data about this form of migration from current research:
Ways into and out of illegality
Illegal residence may arise and end in various ways. Entering a country illegally – for example by sea to the Canary Islands or by land from the Ukraine to the Slovak Republic – is just one route to illegal residence in the European Union. Likely more frequent is when it follows legal entrance, such as when, a person stays in a country after the tourist visa has expired without a residence permit. There are indications in Italy that 75 % of irregular migrants have entered the country legally, 15 % have come illegally across land borders and 10 % across sea borders.
Duration of stay
In the case of irregular migration both limited-term stays and circular patterns of migration are found as well as people settling for an indeterminate period. Stricter border controls tend to lead to an extended period of stay because re-entering the country or moving to and fro is risky.
Wherever possible, irregular migrants avoid contact with government agencies as they are threatened with deportation, imprisonment and often also fines or criminal penalties. For this reason it is difficult to represent them with statistics. As a result, it is only possible to estimate the extent of irregular migration. Estimates as to the number of irregular migrants in Europe have, to date, been neither plausible nor reliable, although there have been efforts made to at least generate greater transparency.
Even if it is not possible to give precise estimations as to the extent, it is at least possible to refer to various indicators in order to analyse trends. On the basis of such analyses, there has been a general worldwide assumption since the end of the 1980s that there has been a sharp increase in irregular migration, although there are certainly also countries where current estimates indicate a declining trend. Germany is one of these countries. After appraising available information and indicators, the German Federal Ministry of the Interior has come to the conclusion that since 1998 "both illegal migration and the number of illegal immigrants appear to have declined."
Origin and motives
Irregular migrants frequently come from nearby countries with a significantly lower level of income, from countries with established historical or current ties with the receiving country, or from countries in which human rights violations or poor economic conditions cause people to emigrate.
Many irregular migrants have a decidedly entrepreneurial attitude. They are capable of earning their living in markets independently and they overcome material difficulties with the help of relatives, friends, acquaintances and also employers. These people form their network. The possibility of activating such networks is also referred to in academic circles as social capital. At the earlier stages, irregular migrants often do not yet have networks but instead just one or a few contacts upon which they are dependent. This makes them vulnerable to false information, deceit or violence. For longer stays, even extensive personal networks have their limits where major problems are concerned, such as accidents or serious health problems.
In Germany, illegal residence is a criminal offence in the eyes of the law; in other countries, such as the Netherlands, it is not. When discussion turns to the association between illegality and criminality, however, generally speaking only such offences are meant as might be committed by a country´s own citizens, such as robbery, assault or theft. Whereas many studies indicate that most irregular migrants avoid criminality in this sense in order to minimize the risk of discovery
Nowadays it can be assumed that irregular immigrants in Europe largely resort to informal markets.