"This is a problem that is unique to software. We wouldn’t permit in any other area of technology the sorts of claims that appear in thousands of different software patents. Pharmaceutical inventors don’t claim “an arrangement of atoms that cures cancer,” asserting their patent against any chemical, whatever its form, that achieves that purpose. Indeed, the whole idea seems ludicrous. Pharmaceutical patent owners invent a drug, and it is the drug that they are entitled to patent. But in software, as we will see, claims of just that form are everywhere."
Professor Mark Lemley of Stanford Law School, on the problem of “functional claiming”, or “patenting the problem, not the solution.”
from The Patent Quality Improvement Act on usv.com