versions.\footnote{There could still exist legal systems, like our modern

  patent system, which could restrict the software in other ways, as well as

  technical measures, such as binary-only distribution, that impeded such activity.}

Software in the real world is copyrighted by default and is

automatically covered by that legal system.  However, it is possible

to move software out of the domain of the copyright system.  A

copyright holder can often \defn{disclaim} their

copyright.  If copyright is disclaimed, the software is not governed

by copyright law. Software not governed by copyright is in the

``public domain.''

\subsection{Public Domain Software}

% FIXME: this section needs more improvements to make it clear that public

% domain dedication is difficult, if not impossible.

% Karen suggests that talking about USA government software being public

% domain might make sense here.

Theoretically, an author can create public domain software by disclaiming all

copyright interest on the work. In the USA and other countries that have

signed the Berne convention on copyright, software is copyrighted

automatically by the author when she ``fixes the software into a tangible

medium.''  In the software world, this usually means typing the source code

of the software into a file.

Carefully note that software in the public domain is \emph{not} licensed

in any way. It is nonsensical to say software is ``licensed for the

public domain,'' or any phrase that implies the copyright holder gave

expressed permission to take actions governed by copyright law.

Section~\ref{Free Software Definition} are all granted because there is no

legal system in play to take them away.

\subsection{Why Copyright Free Software?}

If simply disclaiming copyright on software yields Free Software, then it

stands to reason that putting software into the public domain is the

easiest and most straightforward way to produce Free Software. Indeed,

some major Free Software projects have chosen this method for making their

software Free. However, most of the Free Software in existence \emph{is}

copyrighted. In most cases (particularly in those of FSF and the GNU

Project), this was done due to very careful planning.

Software released into the public domain does grant freedom to those users

who receive the standard versions on which the original author disclaimed

copyright. However, since the work is not copyrighted, any nontrivial

modification made to the work is fully copyrightable.

Free Software released into the public domain initially is Free, and

perhaps some who modify the software choose to place their work into the

public domain as well. However, over time, some entities will choose to

proprietarize their modified versions. The public domain body of software

feeds the proprietary software. The public commons disappears, because

fewer and fewer entities have an incentive to contribute back to the

commons. They know that any of their competitors can proprietarize their

enhancements. Over time, almost no interesting work is left in the public

domain, because nearly all new work is done by proprietarization.