Legal Question in Real Estate Law in California

Send the neighbor a "cease and desist" letter by certified, return receipt mail. Keep a copy. In the letter, give her a reasonable date by which to move it. If the neighbor does not do so, you can file a lawsuit for trespass and seek monetary damages, as well. When you go to court, you should bring a surveyor's report that shows where your property line (and perhaps a Google Earth view) so that the court can see that the mobile home is parked on your property.

Along with Mr. Cohen's sound advice, you'll need to look at how long the neighbor has parked the mobile home on a portion for your property, as well as other circumstances. There may be a claim of prescriptive easement that you'll have to deal with as well as the trespass.

Also, you'll want to be very careful about establishing the fence line. A fence directly on or abutting the property line is called a "division" or "partition" fence, and will usually require your neighbor's consent.

Let me know if you need further information.

Best of luck,

Tom Newton