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 Alabama, adverse possession laws allow a person to acquire legal ownership of a property by possessing it in a manner that is open, notorious, continuous, exclusive, and hostile for a statutory period. The statutory period in Alabama is generally 10 years under Code of Alabama 1975, Section 6-5-200, but it can be reduced to 3 years if the possessor has a just title and pays taxes on the property (Section 6-5-221). Additionally, a 20-year period applies if the possession is under color of title (Section 6-5-202). 'Color of title' means that the person has a document that appears to give them ownership, even if the document has some legal defects. To claim adverse possession, the individual must use the property as a true owner would, without permission from the legal owner, and the use must be so visible and apparent that it gives notice to the legal owner that someone is asserting a claim against their property. If all conditions are met for the requisite time period, the adverse possessor can potentially acquire legal title to the property, which may result in changes to the boundary lines. It is important to note that adverse possession claims can be complex and often require the involvement of an attorney to navigate the legal process.