Several strategies can be employed to fight impunity. First and foremost is to try and break the vicious circle by which those in power protect themselves from prosecution. Individual lawyers, judges and prosecutors have a professional duty to expose those responsible for human rights violations. Often impunity goes hand in hand with corruption. How prosecution in the national judicial process can be improved is elaborated on the legal instruments pages. 
A very special tribunal took place in November 2015 with regard to the human rights violations of 1965/66: The International Peoples Tribunal (IPT 1965). Based on a legal indictment and strengthened by testimonies of witnesses and experts, a quasi-legal procedure was carried out by a Council of Judges. These international human rights law experts concluded in their final statement that it was proven that those human rights violations as such constituted a crime against humanity. This is an important step forward towards an international procedure to come to terms with the past.
On 20 July 2016 the Panel of Judges of the IPT 1965 issued their final Verdict that also made a note on genocide. How effective this initiative will be is yet to be awaited. The Indonesian government quickly responded in the negative.
A second strategy is collecting information on human rights violations and the people who are involved - a strategy of "naming and shaming". This website tries to support that strategy by making accessible and also structuring the information. If not structured, one may easily get overrun with the many loose ends as to trial procedures, which are still pending, never started, or wait for a report. This is what I call "legalized impunity": laws and procedures of law-enforcement are flawed on purpose to make impunity possible. The perspective of "what happened" is available on the events pages in the Documentation section; the perspective of "who did what" is included in the information on the perpetrators pages, also in the Documentation section. All this information has been drawn from public sources.
A third strategy is invoking international human rights law and international procedures. Lacking a special procedure in the context of the United Nations, efforts for invoking the international procedures have to fit into existing monitoring processes, for instance under the International Convention on Civil and Political Rights. Another international opportunity is the Universal Periodic Review in which the human rights situation in a country is scrutinized by other states every four years (http://www.upr-info.org/en) More about these possibilities is to be found on the legal instruments pages.
The monitoring procedures under the different Treaties and Conventions all have their specific opportuinties and limits. The Member-state has to report every two or four years to the independent Committee. At the same time a "shadowreport" is drafted by non-governmental organsations, which is often opposed to the government's vision. The Committee considers both and formulates conclusions that the government will be obliged to apply. Impunity may be tabled under the right to fair trial, the indepenence of judges, etc.(http://www.ohchr.org/EN/HRBodies/SP/Pages/Welcomepage.aspx)
Under international law it has been agreed that impunity concerns the lack of judicial or other prosecution following serious human rights violations such as torture, extra-judicial executions, enforced disappearances and slavery. This implies a limit to those four types of violations for all instruments that can be invoked under international law. It means also that diplomatic interventions will be limited to impunity after those four types of violations (usually called integrity rights, because the violate the integrity of the body). (http://www.ohchr.org/EN/Issues/TruthJusticeReparation/Pages/InternationalInstruments.aspx)
