The two-year long international research project, covering eight countries, financed by the Open Society Foundations, aims at offering possible explanations as to the reasons for similarities and differences regarding the prosecution’s success rate in cases of ill-treatment committed by official persons under different legal regimes. The HHC aims to reveal whether there are any specific legal provisions that prove to be significant factors in the success of investigations and whether any, primarily non-legal factors play an important role in this respect. The pilot phase of the research was launched in 2015, covered Hungary and the United Kingdom and included the preparation of the necessary research tools with the professional supervision of the board set up for the project. Further project partners have been selected from Germany, Northern Ireland, France, the Czech Republic, Belgium, and Bulgaria. Key findings will be summarized in a comparative study and discussed at a closing conference. This will be accompanied by domestic advocacy activities and short videos about the problems identified by the reports.