You mean the concertina?
I can walk over 3 strands with a peice of wood, and have done it before without getting cut up or caught.
You cant walk over the fence and there are video cams and probably some sort of sensors in there as well.
Why would the illegals go over the fence when they could go to Douglas and go over the fence there under the BP's nose like they do now.
The fence keeps them out of private property.
As long as the fence is posted there should be no legal issues. ie this is an intenational border, suject to US laws, private property. Posting the property wont keep people off property, but it pretty much absolves the landowner if someone does something stupid on the property.