Right to light is a form of easement in English law that gives a long-standing owner of a building with windows a right to maintain an adequate level of illumination. The right was traditionally known as the doctrine of "ancient lights". A right to light can also be granted expressly by deed, or granted implicitly, for example under the rule in Wheeldon v. Burrows (1879).
In England, the rights to ancient lights are most usually acquired under the Prescription Act 1832.
In American common law the doctrine died out during the 19th century, and is generally no longer recognized. Japanese law provides for a comparable concept known as nisshōken (日照権, literally "right to sunshine").