Civil Law Rule Legal Definition: Water law: a person who interferes with the natural flow of surface waters so as to cause an invasion of another's interests in the use and enjoyment of his land is subject to liability to the other. Related Terms: Common Enemy Doctrine , Civil Law In Keys v Romney, Justice Mosk wrote:"Diametrically opposed to the common enemy doctrine is the basic civil law rule which recognizes a servitude of natural drainage as between adjoining lands, so that the lower owner must accept the surface water which drains onto his land but, on the other hand, the upper owner has no right to alter the natural system of drainage so as to increase the burden. The doctrine apparently had its inception in Roman law and the Code Napoleon."The civil law rule is that a person who interferes with the natural flow of surface waters so as to cause an invasion of another's interests in the use and enjoyment of his land is subject to liability to the other."The rule finds its justification in the concept that those purchasing or otherwise acquiring land should expect and be required to accept it subject to the burdens of natural drainage. It has the advantage that rights thereunder are readily predictable, and thus tends to avoid the contests likely to occur under the common enemy doctrine."The civil law rule, if strictly applied, admittedly has some tendency to inhibit improvement of land, since almost any use of the property is likely to cause a change in the natural drainage which may justify complaint by an adjoining landowner. As a result, some courts normally applying the civil law rule have suggested that it is not adaptable to the needs of urban communities, where the primary use of land is the erection of structures which are likely to interfere with natural drainage, and accordingly those courts have adopted common enemy or modified common enemy rules in cases involving such land."REFERENCES:Keys v Romley, 64 Cal. 2d 396 (1966) Categories & Topics: Duhaime & Williams Maritime & Waterways Law Dictionary Unless otherwise noted, this page was written by Lloyd Duhaime of Duhaime.org Always looking up definitions? Save time with our search provider (modern browsers only) If you find an error or omission in Duhaime's Legal Dictionary, or if you have suggestion for a legal term, we'd love to hear from you!