The Race Relations Act 1976, s 3(1) defines "racial group” as a group of persons defined by reference to colour, race, nationality, or "ethnic" or national origins.

The quote below is from a ruling by the Law Lords in the Mandla V Dowell Lee (1983) case:

For a group to constitute an ethnic group in the sense of the 1976 Act, it must, in my opinion, regard itself, and be regarded by others, as a distinct community by virtue of certain characteristics. Some of these characteristics are essential; others are not essential but one or more of them will commonly be found and will help distinguish the group from the surrounding community. The conditions, which appear to me to be essential, are these:

1. a long shared history, of which the group is conscious, as distinguishing it from other groups, and the memory of which it keeps alive;
2. a cultural tradition of its own, including family and social customs and manners, often but not necessarily associated with religious observance.

In addition to those two essential characteristics the following characteristics are, in my opinion, relevant:

1. either a common geographical origin, or descent from a small number of common ancestors;
2. a common language, not necessarily peculiar to the group;
3. a common literature peculiar to the group;
4. a common religion different from that of neighbouring groups or from the general community surrounding it;
5. being a minority group or being an oppressed or dominant group within a larger community, for example a conquered people (say, the inhabitants of England shortly after the Norman conquest) and their conquerors might both be ethnic groups.

Treating someone less favourably on the grounds of their religion or belief.
Example: a person is turned down for a job simply because he is a Hindu.

Applying a criterion, provision or practice which disadvantages people of a particular religion or belief.
Example: a no headgear policy applied to all staff disadvantages Sikh staff who wear turbans for religious reasons.

Subjecting someone to unwanted conduct that violates a person's dignity or creates an intimidating, hostile, degrading, humiliating or offensive environment. Example: someone is constantly teased because of his or her beliefs.

A tribunal will take into account the perceptions of the person allegedly discriminated against. However, it will also test whether the action "should reasonably be considered as having that effect".

Victimising someone who has or intends to seek recourse under the regulations or someone who has or intends to give evidence in relation to a complaint of discrimination. Example: denying someone promotion because they supported an employee who took that employer to an Employment Tribunal on grounds of religious discrimination.