In Washington a trespasser may become the owner of property against a neighbor who does not occupy or defend his property over time based on Adverse Possession. The trespasser’s possession must be (1) exclusive, (2) actual and uninterrupted, (3) open and notorious, and (4) hostile for 10 years. The common example involves a boundary dispute where a fence is not located on the true property line. The trespasser then goes on to use all the property within the fence. If the neighbor allows this use to go for a long time without raising objection, eventually the trespasser can claim ownership of all the property inside the fence, including that which originally belonged to his neighbor, by Adverse Possession.