Adverse possession—sometimes called squatter's rights—occurs when a person or entity who does not own a certain piece of real property occupies or uses it in a way that is adverse to the owner of the property—meaning the use is in conflict or at odds with the property owner’s interests.

If this adverse possession or use of the property meets the legal standard for adverse possession—often described as use that is continuous, exclusive, hostile, open, and notorious—and continues for the prescribed period of time (usually specified in the state statute)—the person or entity adversely possessing or using the property will acquire ownership of the property (title). This ownership will result in the changing of boundary lines.

Because the required adverse possession must be open, obvious, and adverse to the owner’s interests, title may only be acquired by adverse possession to the portion of property that is used in that way.

Adverse possession laws vary from state to state and may be located in a state’s court opinions (also known as common law or case law) or, more often, in its statutes.

In Louisiana, adverse possession is governed by state statutes, which differ from the common law tradition followed by many other states. Louisiana law requires a period of possession of 10 years for private property under Civil Code articles 3475 and following. The possession must be continuous, uninterrupted, peaceful, public, and unequivocal. In the case of good faith possessors, the required period is reduced to 10 years if the possessor has just title and has acquired the property in good faith. For bad faith possessors, the period is 30 years, regardless of title. Additionally, the possessor must have the intent to own the property (animus domini), and the possession must be actual, physical, and visible. If these requirements are met, the possessor may acquire ownership of the property through acquisitive prescription, effectively changing the boundary lines. It is important to note that Louisiana's legal system is based on civil law, which is distinct from the common law systems in other states, and thus the specifics of adverse possession laws can be quite different.