Thursday, February 20, 2014

Less may be more: Copyleft, -right and the case law on APIs on both sides of the Atlantic

Abstract: Like any relatively young areas of law, copyright on software is surrounded by some legal uncertainty. Even moreso in the context of copyleft open source licenses, since these licenses in some respects aim for goals that are the opposite of 'regular' software copyright law. This article provides an analysis of the inheritance effect of the GPL-family of copyleft software licenses (the GPL, LGPL and the AGPL) from a mostly copyright perspective as well as an analysis of the extent to which the SAS/WPL case affects this family of copyleft software licenses. In this article the extent to which the GPL and AGPL inheritance clauses have a wider effect than those of the LGPL is questioned, while both the SAS/WPL jurisprudence and the US Google case seem to affirm the LGPL's “dynamic linking” criterium.

A paper by Walter van Holst published in IFOSS Law Review.

Table of content
  • Introduction
  • Legal framework as provided by the GPL family
    • Roles of the GPL family of licenses
    • Bare licenses based on copyright law
  • Analysis and application to libraries
    • Linking mechanisms
    • Transformation and derivation in case law
  • Conclusion


License and attribution
This paper was published in the International Free and Open Source Software Law Review, Volume 5, Issue 1 (MARCH 2013). It originally appeared online at
This article should be cited as follows:
Holst, Walter van  (2013) 'Less may be more: Copyleft, -right and the case law on APIs on both sides of the Atlantic', International Free and Open Source Software Law Review, 5(1), pp 5 – 14
DOI: 10.5033/ifosslr.v5i1.72

Copyright © 2013 Walter van Holst.
This article is licensed under a Creative Commons NL (Netherlands) 2.0 licence, no derivative works, attribution, CC-BY-ND available at
As a special exception, the author expressly permits faithful translations of the entire document into any language, provided that the resulting translation (which may include an attribution to the translator) is shared alike. This paragraph is part of the paper, and must be included when copying or translating the paper.

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