I belived that that the idea here is "inspired by" (Based on the French translation, and the intention expressed in both the English and the French translations of that section of the law.

The use of the word free, in this context, is most probably the idea of "free association," in the psychological sense of free association.

Free implies in this use "independent of," not merely copied.

This from Wikipedia is helpful in terms of "free association" and creative work, highlighting the independence of the new idea from the original.

"Free association is a technique used in psychoanalysis (and also in psychodynamic theory) which was originally devised by Sigmund Freud. ... Subsequently, in The Interpretation of Dreams, Freud cites as a precursor of free association a letter from Schiller, the latter maintaining that, 'where there is a creative mind, Reason - so it seems to me - relaxes its watch upon the gates, and the ideas rush in pell-mell'.[5]
http://en.wikipedia.org/wiki/Free_association_(psychology)

This discussion of copyright where a work is inspired by an author but original thus not subject to copyright is also relevant:

An author may use the works of and be inspired by the
creative expressions of other authors and creators and still satisfy the requirements of originality and creativity in his own work of authorship to acquire property rights in the work created.184 As
authors depend on works of other authors to produce their own
original and creative works of authorship, they bear a moral and
ethical obligation to other authors to ensure the same freedom and rights to access their own works to encourage creative authorship in other authors and creators.
http://ir.lawnet.fordham.edu/cgi/viewcontent.cgi?article=143...

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Note added at 8 hrs (2012-01-30 13:03:42 GMT)
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HERE ARE SOME EXAMPLES FROM UNIVERSITY WEBSITESOF THE USE OF "freely inspired" to mean inspired by but independent of:

This off-the-wall masterpiece by Robert Lepage was freely inspired by fables written by Hans Christian Andersen (who didn't really like children) and explores unraveling relationships, personal demons and compromise that comes too late.
http://www.emerson.edu/news-events/events-calendar?day=31&mo...

"The analysis that follows is freely inspired by a theoretical paradigm known as power resource theory (PRT), which was elaborated to explain the historical trajectory of the
Scandinavian countries ..."
http://digitalcommons.ilr.cornell.edu/cgi/viewcontent.cgi?ar...



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Note added at 16 hrs (2012-01-30 21:29:38 GMT)
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The following may be a different English language translation of the same legislation:

"If any person by using freely a work has created a new and independent work, his copyright shall not be subject to the right in the original work."
Page 92, Swedish copyright law
(Swedish) Law of Decemeber 30, 1960, on Copyright in Literary and Artistic Works
translation by the Swedish Ministry of Justice with amendments of the Swedish Act of June 29, 1970 - Similar Acts have been enacted in Denmark (31/5/1961), Finland (8/7/1961) and Norway (12/5/1961)
http://books.google.com/books?id=XJftyMEyIFMC&pg=PA92&lpg=PA...
Sources of international uniform law
Brill 1973
Konrad Zweigert, Jan Kropholler