Copyright/Sunstein: Woody Guthrie wrote to a song: "This song is Copyrighted in U. S., under Seal of Copyright # 154085, for a period of 28 years, and anybody caught singin it without our permission, will be mighty good friends of ourn, cause we don't give a dern. Publish Publish it. Write it. Sing it. Swing to it. Yodel it. We wrote it, that's all we wanted to do." (1)
Definition Copyleft/Lessig/Sunstein: according to Lawrence Lessig, Copyleft Software is licensed in such a way that future users must require their successors to adopt the same licensing conditions for their work that originate from the copyleft code. The principle is "Share and share the same". (2)
Sunstein: the purpose is that the software remains open when third parties distribute it or something created with its help.
There are different gradations of Copyleft. The most widely used version is GNU General Public License (GPL). (3) This makes it difficult for the developers of proprietary software to integrate open source software into their commercial code.
Copyleft was invented in 1985 by Richard Stallman, who founded the Free Software Foundation FSF in the same year.
1. See Woody Guthrie, http://en.wikipedia.org/wiki/Woody_Guthrie
2. Lawrence Lessig, “Open Source Baselines: Compared to What?,” in Government Policy toward Open Source Software, ed. Robert Hahn et al. (Washington, DC: Brookings, 2002), p. 53.
3. 23. GNU General Public License (vol. 2, 1991), § 2©, available at http://www.opensource.org/licenses/gpl-license.php._____________Explanation of symbols: Roman numerals indicate the source, arabic numerals indicate the page number. The corresponding books are indicated on the right hand side. ((s)…): Comment by the sender of the contribution. The note [Author1]Vs[Author2] or [Author]Vs[term] is an addition from the Dictionary of Arguments. If a German edition is specified, the page numbers refer to this edition.
Cass R. Sunstein
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