India's caste system is perhaps the world's longest surviving social hierarchy. A defining feature of Hinduism, caste encompasses a complex ordering of social groups on the basis of ritual purity.

A person is considered a member of the caste into which he or she is born and remains within that caste until death, although the particular ranking of that caste may vary among regions and over time. Differences in status are traditionally justified by the religious doctrine of karma, a belief that one's place in life is determined by one's deeds in previous lifetimes. Traditionalscholarship has described this more than 2,000-year-old system within the context of the four principal varnas, or large caste categories. In order of precedence these are the Brahmins (priests and teachers), the Ksyatriyas (rulers and soldiers), the Vaisyas (merchants and traders), and the Shudras (laborers and artisans). A fifth category falls outside the varna system and consists of those known as "untouchables" or Dalits; they are often assigned tasks too ritually polluting to merit inclusion within the traditional varna system.

Within the four principal castes, there are thousands of sub-castes, also called jatis, endogamous groups that are further divided along occupational, sectarian, regional and linguistic lines. Collectively all of these are sometimes referred to as "caste Hindus" or those falling within the caste system. The Dalits are described as varna-sankara: they are "outside the system"-so inferior to other castes that they are deemed polluting and therefore "untouchable." Even as outcasts, they themselves are divided into further sub-castes. Although "untouchability" was abolished under Article 17 of the Indian constitution, the practice continues to determine the socio-economic and religious standing of those at the bottom of the caste hierarchy. Whereas the first four varnas are free to choose and change their occupation, Dalits have generally been confined to the occupational structures into which they are born.

The constitution has merely prescribed, but has not given any description of the ground reality. We can make a dent only if we recognise the fact that the caste system is a major source, indeed an obnoxious one, of human rights violations.

With little land of their own to cultivate, Dalit men, women, and children numbering in the tens of millions work as agricultural laborers for a few kilograms of rice or Rs. 15 to Rs. 35 (US$0.38 to $0.88 ) a day. Most live on the brink of destitution, barely able to feed their families and unable to send their children to school or break away from cycles of debt bondage that are passed on from generation to generation. At the end of day they return to a hut in their Dalit colony with no electricity, kilometers away from the nearest water source, and segregated from all non-Dalits, known as caste Hindus. They are forbidden by caste Hindus to enter places of worship, to draw water from public wells, or to wear shoes in caste Hindu presence. They are made to dig the village graves, dispose of dead animals, clean human waste with their bare hands, and to wash and use separate tea tumblers at neighborhood tea stalls, all because-due to their caste status-they are deemed polluting and therefore "untouchable." Any attempt to defy the social order is met with violence or economic retaliation.

As documented throughout this report, the perpetuation of human rights abuses against India's Dalit population is intimately connected to police abuse. Local police officials routinely refuse to register cases against caste Hindus or enforce relevant legislation that protects Dalits. Prejudiced by their own caste and gender biases, or under the thumb of influential landlords and upper-caste politicians, police not only allow caste Hindus to act with impunity but in many cases operate as agents of powerful upper-caste groups to detain Dalits who organize in protest against discrimination and violence, and to punish Dalit villagers because of their suspected support for militant groups.