- The GPL Bargain
- Copyleft and Reciprocity
- Policy Objectives
- The Preamble to the GPL
- GPL as Template
- The GPL Applies to Programs
- Linking to GPL Software
- Copyright Law and Linking
- The LGPL Alternative
- GPL Grant of License
- Access to Source Code
- "At No Charge"
- Other Obligations in the GPL
- The GPL and Patents
- Accepting the GPL
Copyleft and Reciprocity
Partly to emphasize the role of copyright law to protect the freedom of GPL-licensed software and partly to create a catchy term to highlight their focus on software freedom, the authors of the GPL coined the term copyleft to describe its license bargain. It is both a play on the word copyright and an acknowledgment that it promoted a radical (i.e., left-wing, perhaps) departure from traditional software licensing models. The role of a copyleft software license is to grow the public commons of software rather than allow each owner's copyright to pull from that commons.
The Free Software Foundation also describes copyleft as a rule that, when redistributing a program, one cannot add restrictions to deny other people the central software freedoms. The word restriction is very vague in a licensing context; almost any of the terms and conditions in a license can be described as a restriction of some sort. This limitation on restrictions in the definition of copyleft causes some attorneys, including me, heartburn. We contend it would be helpful to add some restrictions to open source licenses that the GPL's authors didn't think of when they wrote their license. For example, provisions for defense against patent infringement lawsuits or to protect the licensor's trademarks can be very useful; both provisions are missing from the GPL.
In practice, the Free Software Foundation's restriction on adding restrictions has had the effect of allowing them to veto any restriction they find unacceptableeven those that are improvements over the GPL. Their avoidance of restrictions has delayed the adoption of new and useful licensing concepts for open source software. This topic will be addressed again when I discuss license compatibility in Chapter 10.
I find the word reciprocity to be less alarming and more descriptive than the word copyleft. I particularly like that word because it does not carry with it the reference to restrictions espoused by the Free Software Foundation.
Reciprocity means a mutual or cooperative interchange of favors or privileges. Something is reciprocal when it is performed, experienced, or felt by both sides. (The American Heritage Dictionary of the English Language, 4th edition.)
The GPL license is reciprocal, because it is "performed, experienced, or felt" by both sidesthe licensor and the licensees both use the GPL.
For these reasons, I refer to reciprocity rather than copyleft. The term copyleft, of course, needn't disappear. It still has great rhetorical value. It is a useful word to toss back at those who mistakenly complain that the GPL destroys copyrights; the GPL requires copyright law to create a copyleft bargain. But I do not find the term useful and I won't use that word again in this book.
Reciprocity provisions are now quite common in open source licenses; the GPL is merely the first and most influential proponent of that particular software bargain. The reciprocity obligations of other open source licenses are subtly different. I shall explore those differences when the individual licenses are discussed. But first, I must explore the policy objectives of the GPL, as much as possible in its authors' own words.