Legal Question in Real Estate Law in California

Probably. The ultimate answer to this type of question is always very dependent on the facts and details of the situation. You really will need to sit down with a knowledgeable real estate attorney to get a reliable answer. Coincidentally, I have a long standing client in Oakhurst, and am in your area several times a year. If you would like further help with this from me, or a referral to someone with an office in your area, please let me know.

The issue would be whether the neighbor has acquired either ownership by adverse possession or an easement by prescription.

The legal requirements for either are rather specific in theory, somewhat less so in actual practice. Applying the law to a particular real-life situation is not always that simple. For example, ownership by adverse possession requires that the claimant have paid the property taxes on the disputed land for five years. Does the tax bill paid by the claimant neighbor or by the owner of record cover the disputed area? Did the assessor work from the legal descriptions of the neighboring parcels, or from going out and looking at them?

Prescriptive easements don't have any payment-of-taxes requirements, but similar to adverse possession does require open and notorious use of the property for at least five years, without permission.

The actual locations of fences and gates and other local specifics may end up being controlling. I do recommend trying to negotiate a settlement of the boundary and land-use issues, and getting it in writing. If the neighbor needs the acre for his operations, a rental for grazing purposes could be part of the deal.