Based on the facts you describe, it is highly doubtful prescriptive rights have been acquired. The key is not whether he knowingly trespassed (i.e. his intent) but rather whether the use of your land was sufficient to put you on notice that he believed he had a right to use your land.
This response is for informational purposes only and is not legal advice, nor does it rise to an attorney client relationship. You should not act upon this information without seeking professional legal counsel.
I agree with Attorney Guerin. I would add that the use of the property must have gone on for 15 uninterrupted years, in order for him to gain any kind of rights.
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