Software patents continue to drag down competition and innovation. The troubling news that a consortium of huge companies is using Nortel's patent portfolio to attack competitors underlines the problem. Continuing their war on Android using purchased patents rather than fair competition, the funders of Rockstar highlight the need for both patent reform and patent defenses.

While many open source advocates remain rightly concerned about the chilling effect of software patents on both innovation and collaboration, open source software has additional defenses against patent aggression that aren't available to proprietary software. The Open Invention Network (OIN), a novel patent pool fighting for rather than against open source, plays an important role in these defenses.

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1. The defensive patent pool

Eight years ago, in November 2005 -- at a time when the challenges from patent trolls and anticompetitive use of patents by market giants were small -- IBM, NEC, Novell, Philips, Red Hat, and Sony formed the Open Invention Network in order to protect Linux and open source. Back then, it required foresight to see that patents would become a major competitive weapon for technology companies, but today the value of OIN is obvious.

OIN's network of licensees now numbers more than 600 companies worldwide. The list of open source software those licensees are committed to defend extends far beyond Linux to embrace even recent innovations. For example, MongoDB is included in the updated list that became effective in September.

Amazingly, the defenses offered by OIN are free of charge. As long as you are willing to commit to not initiating patent litigation against the software in OIN's list and to offering your own patents in defense of that software, you can benefit from access to hundreds of thousands of patents cross-licensed by the network.

It's easy to sign up, too. OIN recently introduced an online system that allows your company to sign up without the need for paper forms. (Tell 'em I sent you!)

OIN is the first tool on my list, and it's one you should seriously consider adopting. But the defenses that clear-thinking open source pioneers have created extend far beyond OIN's defensive patent pool and cross-licensing network.

2. The open source license

You may not realize it, but you may already benefit from extensive protection against the companies most likely to hold patents on the software you use. Open source licenses aren't just about giving you the freedom to use, study, improve, and distribute the software. Most modern open source licenses -- especially the Mozilla Public License, the GNU GPLv3, and the Apache Software License -- incorporate some form of reciprocal patent agreement.

Since many of the contributors to open source projects are patent-holding companies, this means you are the automatic recipient of patent licenses. When you innovate and contribute to the project, your innovations share the protection provided by the license.

What must you do to be protected? First, make sure the software you use is under one of these modern licenses; older licenses like BSD and MIT don't mention patents. Second, comply with the terms of the license -- easy enough for almost all open source licenses, especially compared with the labyrinthine complexity of commercial licenses and EULAs. As long as you comply with the terms of the license, you benefit from the protection it offers. Third, work in the open rather than making last-minute contributions. This is good practice anyway, but it adds protection too.