A prescriptive easement—also known as an easement by prescription or an adverse easement—is an easement (right to use property) created by a use of property (the servient estate) that is open, continuous, and adverse to the owner of the property (the servient estate).

To satisfy the requirement that the use be continuous, the use must take place over a required period of time—which may be specified in a state’s court opinions (common law or case law) or in its statutes if the state legislature has written the law regarding easements into statutes or code. If the state legislature has written a law in statutes or codes the law is said to be codified.

In South Dakota, a prescriptive easement is recognized and can be established when a person uses another's property in a manner that is open, notorious, continuous, and adverse for a statutory period. According to South Dakota Codified Laws (SDCL) § 15-3-1, the statutory period required to establish a prescriptive easement is 20 years. This means that the person claiming the easement must have used the property in such a manner for at least 20 years without the permission of the property owner. The use must be such that the property owner has a reasonable opportunity to notice and challenge it, and it must be uninterrupted for the entire period. If these conditions are met, the person using the land may be able to obtain a legal right to continue such use, despite not being the property owner. It is important for property owners to be aware of any unauthorized use of their land to prevent the establishment of prescriptive easements. An attorney can provide specific guidance on the matter, including how to establish or challenge a prescriptive easement in South Dakota.