Tip: while many decisions may be available on several databases, as listed below, the databases do not replicate each others' content, and they may vary in coverage and search methods - so it is always worth trying several databases. For example, decisions of the International Criminal Tribunal for Rwanda are on both the Oxford Reports on International Law and on Westlaw. The Westlaw version is not browseable - it is only searchable by entering search terms, whereas the Oxford version can only be browsed. Both methods may reveal results that the other does not.
The International Criminal Court (ICC) was created and is governed by the Rome Statute of the International Criminal Court (UNTS 2187, 3). It is an independent, permanent court that tries persons accused of the most serious crimes of international concern, namely genocide, aggression, crimes against humanity and war crimes (Article 5 of the Rome Statute). The ICC is not part of the United Nations system. Its seat is at The Hague in the Netherlands.
Decisions of the ICC are available in full text on:
The International Residual Mechanism for Criminal Tribunals ('MICT') began operating in 2010 in parallel with the ICTR and the ICTY. It will continue to operate after the closure of these two Tribunals. The ICTR closed on 31 December 2015 and the ICTY is expected to close at the end of 2017. More about the MICT.
The UN Mechanism for International Criminal Tribunals Case Law Database is a gateway to the jurisprudence of the ICTR, ICTY, and MICT Appeals Chambers. It provides extracts of key judgments and decisions rendered by the ICTR, ICTY, and MICT Appeals Chambers since their inception, as well as to full-text versions of the corresponding appeal judgments and decisions. More about the Case Law Database.
The ICTR was established by the Statute of the International Criminal Tribunal for Rwanda (1994). The ICTR closed on 31 December 2015.
Judgments and other documents regarding each case, such as indictments, minutes and orders, are available on:
The ICTY was established by the Statute of the International Criminal Tribunal for the Former Yugoslavia (1993).
Judgments are available:
Investigating War Crimes in the Former Yugoslavia War 1992-1994 by The Court of Bosnia and Herzegovina is a hybrid tribunal - a domestic court of the State of Bosnia and Herzegovina that includes international judges and prosecutors. It was established on 3 July 2002 by the Parliament of Bosnia and Herzegovina. Under the Constitution of Bosnia and Herzegovina, matters that fall under the jurisdiction of the Court include terrorism, war crimes, human trafficking, organised crime and economic crimes.
Decisions of the BWCC are available on the ICC Legal Tools database (open access).
The Special Tribunal for Lebanon was established by the 2007 Agreement between the United Nations and the Lebanese Republic on the establishment of a Special Tribunal for Lebanon. The mandate of the Special Tribunal for Lebanon is to prosecute persons responsible for the attack of 14 February 2005 resulting in the death of former Prime Minister Rafiq Hariri and in the death or injury of other persons.
The cases link on official STL website contains all public documents, such as indictments, judgments and transcripts, from all cases at the STL.
Decisions are also available on the ICC Legal Tools database (open access).
The Special Panels of the Dili District Court (also called the East Timor Tribunal) was the hybrid international–East Timorese tribunal that was created in 2000 by the United Nations Transitional Administration in East Timor (UNTAET) to try cases of 'serious criminal offences' which took place in East Timor in 1999. The Special Panels sat from 2000 to 2006.
Decisions of the SPSC are available on the open access ICC Legal Tools Database.
The Iraq High Tribunal was established as a domestic court within the national judicial structure. Unlike other as hoc international criminal courts and tribunals, the IHT was not established by treaty or United Nations resolution. The Tribunal Statute provides jurisdiction for certain international crimes committed by Iraqis during the Ba’athist regime, which lasted from July 1968 to May 2003. Article 10 of the Statute includes crimes of genocide, crimes against humanity and war crimes that were previously unknown to Iraqi law.
Decisions of the SPSC are available on the open access ICC Legal Tools Database.
The SCSL was established by the Statute for the Special Court for Sierra Leone (2002) to address serious crimes against civilians and UN peacekeepers committed during the country's decade-long (1991-2002) civil war. The SCSL was the world's first 'hybrid' international criminal tribunal. The Tribunal has completed all its cases and closed in 2013.
The Residual Special Court for Sierra Leone (RSCSL) was established by the 2012 Residual Special Court Agreement (Ratification) Act to oversee the continuing legal obligations of the SCSL after its closure. The RSCSL will remain in existence until all sentences have been served. The residual obligations of the Residual Court include witness protection, supervision of prison sentences, and management of the SCSL archives.
The RSCSL website contains the trial transcripts judgments of the Court, together with all official trial documents. Videos and transcripts are also available.
SCSL decisions are also available on:
The Law Reports of the Special Court for Sierra Leone by 
The Sierra Leone Special Court and Its Legacy: the impact for Africa and international criminal law by The 2003 Agreement between the United Nations and the Royal Government of Cambodia concerning the prosecution under Cambodian law of crimes committed during the period of Democratic Kampuchea established the Extraordinary Chambers in the Courts of Cambodia for the Prosecution of Crimes Committed During the Period of Democratic Kampuchea (“Extraordinary Chambers”).
The official ECCC website includes court documents and live courtroom video streaming.
Decisions are also available on:
Hybrid Justice : The Extraordinary Chambers in the Courts of Cambodia by 
The Extraordinary Chambers in the Courts of Cambodia: assessing their contribution to international criminal law by Oxford University Press's free resource, High-profile prosecutions at the International Criminal Court: heads of state, immunities, and arrests, maps scholarly commentary on the international law aspects of a number of high-profile prosecutions at the International Criminal Court, including those of Kenya’s President Uhuru Kenyatta and Deputy-President William Ruto, and Sudan’s President Omar al-Bashir. The map looks specifically at questions of immunity, the obligation to arrest and surrender, the impact of Kenya’s possible withdrawal from the Rome Statute, and Ruto’s and Kenyatta’s obligations to be present throughout their trials. It brings together discussions in English-language legal blogs and a selection of journal articles.
Universal jurisdiction is the ability of the court of any State to try persons for crimes committed outside its territory that are not linked to the State by the nationality of the suspect or the victims or by harm to the state’s own national interests.
An example of universal jurisdiction is the trial and conviction of Hissène Habré in 2016 by the Extraordinary African Chambers in Senegal (EAC), in which the Senagalese domestic courts found the former Head of State of Chad criminally responsible for crimes against humanity, war crimes and torture. These crimes were committed in Chad between 1982 and 1990. The Statute of the Extraordinary African Chambers created the EAC to prosecute these international crimes. It was an ad hoc chamber established within the Senegalese courts by agreement between the African Union and the government of Senegal. More on the trial and its significance from AfricLaw. More on the EAC from the International Justice Monitor.
Amnesty International has published UNIVERSAL JURISDICTION: A PRELIMINARY SURVEY OF LEGISLATION AROUND THE WORLD - 2012 UPDATE