The term "selection" patent, which is widely used outside the United States, is one that was until recently unknown to most United States patent practitioners, and although some court decisions have hinted that the selection patent concept may be useful. Before reviewing the cases, however, it is worth reminding ourselves that an enquiry into the obviousness of a claimed invention is a two step process first to consider whether what is claimed is prima facie obvious and second, if it is whether the applicant or patentee can rebut that initial finding by showing something surprising or superior about what is claimed. In the case of In re Jones [178] the Federal Circuit Court of Appeals held that a novel ammonium salt of a known herbicidal compound was patentable despite the prior publication of the genus of ammonia salts of the compound and specific discussion of certain of them. The court took the view that the prior publication was of a "potentially infinite genus" of such ammonia salts and held that the compound claimed was not "sufficiently similar in structure to (the compounds of the prior art) as to render it prima facie obvious". Thus the fact that the evidence submitted by the applicant to try to show advantageous properties for his salt was not particularly convincing did not preclude the patentability of the compound claimed.

In In re Baird [179] the Federal Circuit built on the Jones decision citing this as precedent for the proposition that "The fact that a claimed compound may be encompassed by (prior) disclosed generic formula does not by itself render that compound obvious". The court went on to find that the prior generic disclosure did not "teach or fairly suggest selection" of the compound now claimed, pointing out that the specific teaching of the prior art had been of complicated analogs of the compound now claimed and that “ A disclosure of millions of compounds does not render obvious a claim to three compounds, particularly when that disclosure indicates a preference leading away from the claimed compounds”. Following the Baird decision the Patent Office issued guidelines according to which the question to be decided in species-genus situations was the same as considering all other cases of obviousness namely whether the prior teaching provided any motivation to produce what was now being claimed. Such consideration requires looking at predictability in the particular art, the properties of the species as compared to those taught for the prior genus and the closeness in structure of the claimed species to typical or preferred species taught in the prior generic disclosure.