Belgium

Article 1383 of the Belgian Civil Code foresees in a so called “general standard of care”, meaning that one may not merely determine his conduct in function of his own interests, but that he/she also must take precautions in order to prevent damage to other persons or goods.
Of course, the question is what the level of precaution is that one must take in consideration, in order to prevent that damage is done to other persons. Therefore, one must make an abstract comparison between the person concerned and the assumed behavior (precautions) a normal and careful person, placed in the same concrete external circumstances, would take into account.
If the conclusion is that the person concerned has not taken the measures that a normal and careful would have taken in the same (external) circumstances, and this resulted in damage to other persons or goods, the person concerned will be held liable.
It goes without saying that this will be a question of fact which depends on the concrete circumstances.
The aforementioned general principle can by analogy be applied to individuals or companies that provide services by means which requires an IT network or IT software, in which case they have to take appropriate IT security measures which a normal and care person – providing the same or similar services – would take, and taking into account the current state of technology.