German anti-socialist laws, first implemented in 1878, expire. At
the Erfurt Congress soon after, the Social Democratic Party openly
adopt a Marxist programme for the first time.
Citation:
Editors. "German anti-socialist law of 1878 expires".
The Literary Encyclopedia. First published 30 December 2011
[http://www.litencyc.com/php/stopics.php?rec=true&UID=19039, accessed 23 May 2013.]