Adjoining landowners are those persons, such as next-door and backyard neighbors, who own lands that share common boundaries and therefore have mutual rights, duties, and liabilities. The reciprocal rights and obligations of adjoining landowners existed at common law but have been modified by various state laws and court decisions. For example, adjoining landowners are expected to use their property reasonably without unduly interfering with the rights of the owners of contiguous land. Anything that a person does that appropriates adjoining land or substantially deprives an adjoining owner of the reasonable enjoyment of his or her property is an unlawful use of one’s property.
Property owners have the right to grade or change the level of their land or to build foundations or embankments so as long as proper precautions are taken, such as building a retaining wall to prevent soil from spilling upon adjoining land.