The theory of natural law[->4] is closely related to the theory of natural rights. During the Age of Enlightenment[->5], natural law theory challenged the divine right of kings[->6], and became an alternative justification for the establishment of a social contract[->7], positive law[->8], and government[->9] — and thus legal rights — in the form of classical republicanism[->10]. Conversely, the concept of natural rights is used by some anarchists[->11] to challenge the legitimacy of all such establishments.[1]HYPERLINK \l "cite_note-2"[2]
The idea of human rights[->12] is also closely related to that of natural rights; some recognize no difference between the two and regard both as labels for the same thing, while others choose to keep the terms separate to eliminate association with some features traditionally associated with natural rights.[3] Natural rights, in particular, are considered beyond the authority of any government or international body[->13] to dismiss. The Universal Declaration of Human Rights[->14] is an important legal instrument[->15] enshrining one conception of natural rights into international soft law[->16]. Natural rights were traditionally viewed as exclusively negative rights[->17],[4] whereas human rights also comprise positive rights.[5]
The idea that animals have natural rights[->18] is one that has gained the interest of philosophers and legal scholars in the 20th century,[6] Even on a natural rights conception of human rights, the two terms may not be synonymous.
The legal philosophy known as Declarationism[->19] seeks to incorporate the natural