in English property law, the right of a building or house owner to the light received from and through his windows. Windows used for light by an owner for 20 years or more could not be obstructed by the erection of an edifice or by any other act by an adjacent landowner. This rule of law originated in England in 1663, based on the theory that a landowner acquired an easement to the light by virtue of his use of the windows for that purpose for the statutory length of time. The doctrine did not acquire wide acceptance by courts in the United States.