That people are different and diverse is an accepted fact. Exclusion and discrimination arise when distinctive features are loaded with negative meaning, which is then projected onto individuals bearing such features. Therefore, it is understandable that individuals falling into a certain group reject any categorisation to circumvent exclusion and discrimination. This may particularly manifest itself in the context of the collection of data regarding ethnic origin, affiliation, or attribution. This can be explained by looking at German pre-war history, which is dominated by imposed labels such as ‘Jews’, ‘Gypsies’ and, ‘disabled’.

The principle of self-identification, as part of data collection, attempts the opposite. Interviewees identify themselves as members of a particular group (or not). They have the freedom to assign themselves to a category and remain in complete control. Whether outsiders perceive this as ‘right or wrong’, or ‘appropriate or not’ is irrelevant. No one is entitled to question or change this identification. This principle must remain unchallenged, even if the person chooses to change their identification. It would therefore be possible and understandable if the grand-daughter of a Turkish guest worker were to identify on some occasions in surveys as Turkish, and in others as German.

In 1990, the UN Committee on the Elimination of Racial Discrimination (CERD) introduced the principle of self-identification as part of its General Recommendation Number 8. The principle is supported by the ‘European Commission Against Racism and Intolerance’ of the Council of Europe. According to the Framework Convention for the Protection of National Minorities of the Council of Europe, members of national minorities are endowed with the right to self-identification.

The principle of self-determination, as enshrined in these international treaties, must be provided in domestic law, as well as in the context of concrete situations where sensitive data is collected. Only then can the concerned communities be expected to support data collection.