According to Massachusetts’ law, if a person openly and continuously uses your land without your permission for 20 years or more, that person can take ownership of the land he used.
This is the doctrine of adverse possession.
For example, say your neighbor builds a fence.
The fence extends five feet onto your property.
It remains in place without your permission for 20 years.
At that point—after 20 years of the fence being on your property—you can no longer force the neighbor to move it.
In fact, the neighbor can seek a court judgment establishing his ownership of the portion of your land encompassed by the fence.
In this video I discuss the doctrine of adverse possession and explain how you can prevent your neighbor from making claims to your land.
If you have any questions regarding property law, please contact me at firstname.lastname@example.org