A loint of paw

Trespass is defined as the unauthorised interference with the possession of your home and garden. The law says you have the right to decide what is left on your property, as well as the right to keep people out.
Most people protect their homes and gardens by building a fence, for which you won't normally need planning permission unless it is more than two metres high.
Signs that read "Trespassers will be prosecuted" are meaningless as you cannot be prosecuted for trespass - it is a civil wrong, not a criminal offence. It's therefore more accurate to have a sign that reads: "Keep out - private property. You are trespassing."
"A Loint of Paw" is a vignette by Isaac Asimov, first published in The Magazine of Fantasy & Science Fiction in August 1957. It was reprinted in the 1968 collection Asimov's Mysteries and the 1986 collection The Best Science Fiction of Isaac Asimov.