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 Colorado, adverse possession is governed by state statutes, specifically under Colorado Revised Statutes sections 38-41-101 to 38-41-112. The law requires that the possession be hostile, actual, open, exclusive, and continuous for a statutory period. In Colorado, the statutory period for adverse possession is typically 18 years, but it can be reduced to 7 years if the adverse possessor has color of title (a claim founded on a written instrument like a deed or a will) and has been paying property taxes. Additionally, Colorado has a unique requirement known as 'good faith' which means the adverse possessor must have had a reasonable belief that they were the actual owner of the property during the time of possession. If all legal requirements are met, the adverse possessor can potentially acquire legal title to the property. It is important to note that adverse possession cases can be complex and fact-specific, and an attorney can provide guidance on the likelihood of success in a claim for adverse possession.