Political theorists since the time of the ancient Greeks have argued in support of the existence of natural rights, meaning those rights that men possessed as a gift from nature (or God) prior to the formation of governments. It is generally held that those rights belong equally to all men at birth and cannot be taken away.
The concept of natural rights received one of its most forceful expositions in the writings of Englishman John Locke (1632-1704), who argued that man was originally born into a state of nature where he was rational, tolerant, and happy. In this original existence man was entitled to enjoy the rights of life, liberty and property.
However, not all men chose to live within the confines of the natural laws and presented threats to the liberties of the others. At this stage man entered into a social contract (compact) in which a state (government) was formed to guarantee the rights of the members of society.
Locke believed that the only reason for the existence of government was to preserve natural rights and, by extension, mans happiness and security.
These ideas were eagerly accepted by many American colonists in the 18th century, an age when political philosophy was widely read and discussed. James Otis made an eloquent appeal to natural rights in his argument against the writs of assistance in 1761 and Thomas Jefferson offered a classic restatement in the Declaration of Independence in 1776.