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 Iowa, adverse possession laws require that the possession of the property by a non-owner must be hostile, actual, open, exclusive, and continuous for a statutory period of 10 years (Iowa Code § 560.1). The possessor must treat the property as their own, without the permission of the actual owner, and their possession must be known to others. If these conditions are met for the full period, the possessor may be able to claim legal title to the property. It's important to note that adverse possession claims can be complex and may require the involvement of an attorney to navigate the legal process. Additionally, the actual owner may have defenses against an adverse possession claim, such as proving that the use of the property was with the owner's permission. Boundary lines can indeed be changed as a result of adverse possession, but this typically requires a legal action to quiet title to formally establish the new property lines.