SPS owned a patent for apparatus for catching debris in a well bore designed for use in the oil and gas drilling industry. The apparatus incorporated a filter through which the well fluid was circulated, to remove debris. Smith applied to revoke the patent on the ground that the invention claimed was not novel and/or did not involve an inventive step. Even after SPS amended its claims, the Patent Office concluded that claim 1 of the patent had been anticipated by prior art but that most of the rest of the patent was fine. SPS appealed against the ruling on claim 1; Smith cross-appealed against the other rulings.
The IPKat says: "this is one of those cases that seems to turn pretty well entirely on the facts, with no real law in it". Merpel adds, "at least we know that Lewison J is still doing patent cases. He doesn't seem to have had one for ages".
Well bores here and here
Small bores here and here
Big bores here; big boars here