Legal Question in Real Estate Law in New York

Re: Fence on my property

This is a trespass and you can bring an action to have it removed. In the alternative you need a an agreement with them that while they can use your property for the fence it is understood you still own it otherwise eventually they may claim ownership of the land. Good luck.

Re: Fence on my property

If you can establish by survey, rather than by arbitrary means, that the fence is on your property, you can compel him to remove it, plus recover any costs you incurred (e.g., the new survey). If he refuses, he can be sued for taking your property for which you can be compensated, or have the court order the fence's removal. If you do nothing, he could over time be considered as acquiring your property bounded by the fence, by adverse possession. I suggest you contact your neighbor before spending money and see how he reacts. If he refuses to remove the fence then proceed as I have suggested.