Software patents have been an agent of change in open source over the last decade, as I explained in my keynote at the 8th International Conference on Open Source Systems this week. Most notably, the astonishing proliferation of software patents has forced technology companies to spend a lot of time and energy assembling defensive portfolios.

Moreover, software patents are written to cover not just the implementation of an invention but also its function -- the idea behind it. The result: a fearsome threat to even the richest corporation, effectively closing whole areas of markets, no matter how innovative the alternative. Open source developers in particular have expressed concern because many of them have no corporate employer to defend them in the event of an attack by a patent holder. Software patents are bogeymen that every open source community must deal with.

[ Read up on Simon Phipps' classic post, "Why software patents are evil." | Track the latest trends in open source with InfoWorld's Technology: Open Source newsletter. ]

How is the open source community responding to the threat of software patents? Let me count the ways:

The insertion into open source licenses of both patent grants to accompany source code contributions and patent "peace agreements" that threaten mutually assured destruction to licensees who engage in patent hostility

The issuance of guidance to community members on how to treat patents and patent threats, such as that created by the Debian project

The use of contribution agreements to get backup patent protections from contributors, such as that used by the Apache Software Foundation

The creation of an extensive cross-community, cross-industry defensive patent pool for Linux in the form of the Open Invention Network

A broad defensive scheme to publish details of innovations in open source so that any future patents claimed against it can be invalidated

What if all this effort could have been avoided simply be re-reading the law Congress wrote and understanding it differently? That's the amazing claim made by Professor Mark Lemley of Stanford University in a new paper to be presented in October at the University of Wisconsin entitled "Software Patents and the Return of Functional Claiming."

The fallacy of "functional claiming"

Lemley's thesis is radically simple: "Most software patents today are written in functional terms," he writes. "If courts would faithfully apply the 1952 Act, limiting those claims to the actual algorithms the patentees disclosed and their equivalents, they could prevent overclaiming by software patentees and solve much of the patent thicket problem that besets software innovation."

In other words, when we say patents protect inventions, what we mean is they protect specific solutions to problems, rather than the idea of solving a particular problem. The design for a plough can be patented; the idea of ploughing a field can't. A specific new drug that stops a headache can be patented; the function of using a drug to stop a headache can't. Lemley explains how patent applications were increasingly written to go outside these bounds, culminating in a case in the 1940s where a judge finally declared patent claims that attempted to fence off a function -- "functional claiming" -- as an invalid use of patents.