Easement

An easement is a non-possessory property interest that allows the holder to use someone else's land for a defined purpose, such as crossing it, laying utility lines, or drawing water. The parcel burdened by the easement is called the servient estate; the parcel that benefits (where applicable) is the dominant estate. Easements are typically classified along two axes:

• Appurtenant vs. in gross — Easements appurtenant attach to a particular piece of land and transfer automatically when that land is sold. Easements in gross belong to a person or entity (commonly utility companies or governments) regardless of land ownership.
• Affirmative vs. negative — Affirmative easements let the holder do something on the servient land (e.g., drive across it). Negative easements restrict what the servient owner may do (e.g., block light or a scenic view).

Easements can be created by express grant or reservation in a deed, by implication when a property is subdivided, by necessity (commonly for landlocked parcels), by prescription (long, open, continuous, and adverse use over a statutory period), or by estoppel. They are generally extinguished by release, merger of the two estates, abandonment, or expiration of their stated term.

In public policy, easements play a significant role beyond private disputes. Conservation easements, recognized in U.S. law and supported by Internal Revenue Code §170(h), let landowners permanently restrict development in exchange for tax benefits, and are widely used by land trusts such as The Nature Conservancy. Public access easements secure rights-of-way for trails or coastlines. Governments may also acquire easements through eminent domain, paying just compensation rather than buying the land outright — a common approach for pipelines, transmission corridors, and highway sightlines.

While easement doctrine is rooted in common law, civil-law systems recognize a closely analogous concept called servitudes, codified for example in the French Civil Code.