The Spanish criminal justice system, where the societas delinquere non potest principle was
traditionally a canon, was gradually being opened up with measures for companies involved in
criminal practices, especially incidental consequences of the penalties for individuals. In 2010, the
corporate criminal liability was finally fully embraced, with a regulation that was thoroughly revised
in 2015 to give more prominence to the role of compliance programmes. It is assumed that these
programmes not only seek to ensure that the company itself prevents crimes from being committed
within it but also encourage the provision of information in criminal proceedings, information that
would otherwise be difficult for the prosecution to obtain and which is therefore rewarded by using
the principle of opportunity in the process. The aim of this paper is to expose the risks posed by the
internal investigations encouraged by compliance programmes for the fundamental rights of workers,
such as privacy, honour, the secrecy of communications or their own right of defence, since the worker
has a weaker position in relation to the company than the citizen in relation to the state. Furthermore,
the very evidence obtained through this investigation may be excluded from the proceedings because
of its collision with the rights of the worker.