ANCIENT LIGHTS, a phrase in English law for a negative easement (q.v.) consisting in the right to prevent the owner or occupier of an adjoining tenement from building or placing on his own land anything which has the effect of illegally obstructing or obscuring the light of the dominant tenement. At common law a person, who opens a window in his house, has a natural right to receive the flow of light that passes through it. But his neighbour is not debarred thereby from building on his own land even though the effect of his action is to obstruct the flow of light thus obtained. Where, however, a window had been opened for so long a time as to constitute immemorial usage in law, the light became an “ancient light” which the law protected from disturbance. The Prescription Act 1832 created a statutory prescription for light. It provided (s. 3) that “when the access and use of light to and for” (any building) “shall have been actually enjoyed therewith for the full period of 20 years without interruption, the right thereto shall be deemed absolute and indefeasible, any local usage or custom to the contrary notwithstanding, unless it shall appear that the same was enjoyed by some consent or agreement, expressly made or given for that purpose by deed or writing.” The statute does not create an absolute or indefeasible right immediately on the expiration of twenty years. Unless and until the dominant owner’s claim is brought into question (s. 4) no absolute or indefeasible title can arise under the act. The dominant owner has only an inchoate right to avail himself under the act of the twenty years’ uninterrupted enjoyment, if his claim is brought into question. But in the meantime, however long the enjoyment may have been, his right is just the same, and the origin of his right is just the same as if the act had never been passed. These principles were laid down in 1904 by the House of Lords in the leading case of Colls v. Home & Colonial Stores Ltd. (1904 A.C. 179). They overrule an earlier view propounded by Lord Westbury in 1865 (Tapling v. Jones, 11 H.L.C. 290) that the Prescription Act 1832 had abrogated the common law prescription as to light, that the right to “ancient lights” now depends upon positive enactment alone, and does not require, and ought not to be rested on, any fiction of a “lost grant” (see Easement). There has been much difference of judicial opinion as to what constitutes an actionable interference with “ancient lights.” On the one hand, the test has been prescribed that if an angle of 45°—uninterrupted sky light—was left, the easement was not interfered with, and, while this is not a rule of law, it is a good rough working criterion. On the other hand, it was held in effect by the Court of Appeal in the case of Colls v. Home & Colonial Stores Ltd. (1902; 1 Ch. 302) that to constitute an actionable obstruction of ancient lights it was sufficient if the light was sensibly less than it was before. The House of Lords, however, in the same case (1904 A. C. 179) overruled this view, and held that there must be a substantial privation of light enough to render the occupation of the house or building uncomfortable according to the ordinary notions of mankind and (in the case of business premises) to prevent the plaintiff from carrying on his business as beneficially as before. See also Kine v. Jolly (1905, 1 Ch. 480).
There is, in Scots law, no special doctrine as to “ancient lights.” The servitude of light in Scotland is simply the Roman servitude non officiendi luminibus vel prospectui (see Easement and Roman Law). The same observation applies to the Code Civil and other European Codes based on it. The doctrine as to ancient lights does not prevail generally in the United States (consult Ruling Cases, under “Air”).