The German government objects to the fact that Italy continues to allow claims for individual reparations by relatives of victims of German war crimes, although the court has long since declared this inadmissible, the ICJ announced in The Hague, reported dpa.
Such a dispute in court between two such close partner countries is very unusual.
In 2012, the court had already ruled that Germany did not have to compensate Italian victims of Nazism individually and that corresponding Italian judgements were invalid.
With its lawsuit, Germany is now insisting that Italy recognize the principle of immunity of states in civil lawsuits in other states, which was established in the ruling handed down 10 years ago.
The German Wehrmacht and the SS had wreaked havoc in many places during their retreat from Italy in World War II. Many Italians were also murdered in the process.