The Stockfish project, which
distributes a chess engine under GPLv3, has announced
the filing of a GPL-enforcement lawsuit against ChessBase, which has been
(and evidently still is) distributing proprietary versions of the Stockfish
code.
In the past four months, we, supported by a certified copyright and
media law attorney in Germany, went through a long process to
enforce our license. Even though we had our first successes,
leading to a recall of the Fat Fritz 2 DVD and the termination of
the sales of Houdini 6, we were unable to finalize our dispute out
of court. Due to Chessbase’s repeated license violations, leading
developers of Stockfish have terminated their GPL license with
ChessBase permanently. However, ChessBase is ignoring the fact that
they no longer have the right to distribute Stockfish, modified or
unmodified, as part of their products.