After a long running legal battle, started in 1997 when producer Moses Pelham used a clip from Kraftwerks Metal on Metal in a track, the supreme German Constitutional Court has found in favour of Moses Pelham.
The court agreed that,
artistic freedom overrides the interest of the owner of the copyright.
…and that sampling should be permitted if it does not constitute direct competition to the sampled work, and does not damage the rights-holders financially.
More details online.