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Is public domain software open-source?

There's no doubt that open-source software and that in the public domain are similar. But even experts differ about just how closely linked they are.

Stephen Shankland principal writer
Stephen Shankland has been a reporter at CNET since 1998 and writes about processors, digital photography, AI, quantum computing, computer science, materials science, supercomputers, drones, browsers, 3D printing, USB, and new computing technology in general. He has a soft spot in his heart for standards groups and I/O interfaces. His first big scoop was about radioactive cat poop.
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Stephen Shankland
3 min read

When writing earlier this week about Adobe's sponsoring of the SQLite project, I ran into a complicated issue: is software released into the public domain also open-source software?

I have an editor who hates headlines with question marks, but I'm afraid this time it's appropriate, because even experts disagree.

For background, software or other material in the public domain simply means that it's not copyrighted. Requirements to meet the official Open Source Definition are listed by the Open Source Initiative. Two programmers, Eric Raymond and Bruce Perens, founded the OSI about 10 years ago to formalize and codify the open-source idea as it branched off the free-software movement Richard Stallman founded in the 1980s, and OSI lists 68 compliant licenses.

Richard Hipp, who founded the SQLite database project in 2000 as a public-domain project, believes it does qualify as open-source software.

"I've had a number of conversations on this topic with corporate lawyers for companies that are actively using SQLite. The consensus there seems to be that 'public domain' is valid and is a proper subset of 'open source'--except in France and Germany where the concept of 'public domain' is not recognized," he told me in an e-mail discussion prompted by the Adobe story.

But not so fast. Take the view of Mark Radcliffe, the intellectual property attorney who's general counsel to the Open Source Initiative.

When I asked Radcliffe if public domain software was open-source, he was clear: "No. Truly public domain software is no longer protected by copyright, thus it cannot have a license which would impose the terms necessary to comply with any of the open source licenses," he said.

Agreeing with him is Louis Rosen, an attorney with Rosenlaw and Einschlag who previously led OSI's legal work and who still is involved. He directed me to an older but still relevant piece he wrote about why the public domain isn't a license.

"'Public domain' will never be a license. It actually means 'No license required,'" Rosen said. "Software that is 'dedicated to the public' or 'to the public domain' is pretty safe. I just worry a bit when people or companies give software away in such an amateurish way, without understanding that licenses or covenants are far more efficient and effective."

While "public domain" isn't a license on OSI's official list of open-source licenses, Perens said it's not far off: "Software that has been formally dedicated to the public domain through some sort of written statement meets the requirements of the Open Source definition only if the source code is available. Surprisingly, 'public-domain' binary-only software exists in some odd corners of the Net."

And Raymond added, "Public-domain software qualifies...The users are guaranteed all the redistribution and reuse rights that the Open Source Definition seeks to secure by the fact that there is no owner to enforce restrictions."

Moving from the theoretical realm into the practical, though, the SQLite project appears more open-source than not. The project's source code is available without restriction, and programmers who contribute code it to it must explicitly declare their contribution is given to the public domain for perpetuity, which appears to satisfy Perens' opinions.