On November 6, 1455 Johann Fust, a merchant and money-lender, filed a lawsuit at the Court of the Archbishop of Mainz against Johannes Gutenberg to recover money that he had advanced to Gutenberg beginning in 1450. This is one of the few extant documents that may imply Gutenberg's place in the history of printing by movable type, though nothing concerning printing is specifically mentioned in the document. It is also possible, according to Paul Needham, that the surviving document may be Gutenberg's personal copy, endorsed in his hand.
Fust's total claim against Gutenberg was 2026 gulden with interest. As a result of the lawsuit Gutenberg most probably paid back Fust's investment plus interest. Whether Fust gained possession of Gutenberg’s press and equipment, used for what the document calls the "Work of the Books," is unclear. Gutenberg seems to have resumed printing before 1460.
The record of this lawsuit, preserved at the Niedersächische Staats- und Universitäts Bibliothek Göttingen, is formally known as the The Helmasperger Notarial Instrument.
"Ulrich Helmasperger, clerk of the Bishopric of Bamberg, royal notary and certified public recorder at the Court of the Archbishop of Mainz wrote the Instrument which bears his name. This is the only contemporary account of the business relations between Gutenberg and Fust and of Gutenberg's invention, the "Work of the Books". This account of the legal proceedings documents that the citizen of Mainz, Johannes Fust, swore the following under oath: He had lent Gutenberg the sum of 1550 guilders which he himself had had to borrow at an interest rate of 6%. In his view the money he lent Gutenberg which was not used for their mutual benefit for the Work of the Books was a loan and thus he demanded that the interest on this loan be refunded to him. The Instrument briefly discusses the first legal complaint - the demand for repayment of the money - and describes the judgement which was unfavorable for Gutenberg. The Instrument does not mention the final judgement - Fust's demand that the partnership with Gutenberg be dissolved and the consequences of this" (http://www.gutenbergdigital.de/gudi/eframes/index.htm, accessed 01-17-2010).
♦ You can view a digital facsimile of the document, in whole, and in enlarged parts with transliterations and English translations, from the Niedersächische Staats- und Universitäts Bibliothek Göttingen website at this link: http://www.gutenbergdigital.de/gudi/eframes/index.htm, accessed 01-17-2010).
Needham, The Invention and Early Spread of European Printing as Represented in the Scheide Library (2007) 8.