Listening to commentators reporting on the Supreme Court hearing it was clear that it was going to be difficult for the Court to come up with detailed guidance. But is guidance what we really want? Patent offices around the world like guidance because it helps them carry out a step by step analysis to reject (or uphold) elegibility for patent protection. Practitioners love guidance - but only when it is in their favour. Then they have a cogent basis for arguing patentability (or non-patentability).
But really the guiding light in Bilski is the common sense approach that you do not rewrite words of a statute in different words. Maybe we could have done better with that in Europe. It may make the margins more difficult to apply, but it has the merit of not undermining the original statutory intent, and furthermore, because that intent was many many years ago, the courts show a commendable measure of flexibility in favour of justifiable innovation but to exclude unjustifiable innovation. Admittedly so far as the judges think it so.