During a hearing on Wednesday at the International Criminal Tribunal for the former Yugoslavia (ICTY), judges upheld the war crimes conviction and announced a 20-year jail term for Slobodan Praljak, an ex-commander of Bosnian Croat forces. Upon hearing the verdict, Praljak said he was not a criminal and then drank from a bottle containing poison.

Here is what you should know about war crimes:

1. War crimes are acts that violate the international laws, treaties, customs, and practices governing military conflict between belligerent states or parties. War crimes and crimes against humanity are among the gravest crimes in international law.

2. In modern international law, war crimes are defined by the Geneva Conventions, the precedents of the Nuremberg Tribunals, the Laws and Customs of War, and the statutes of the International Criminal Tribunal in The Hague.

3. The specific determination of what constitutes a war crime varies based on various international conventions and nation-state statutes. But the acts that are generally considered to constitute a war crime include: Atrocities or offences against persons or property, constituting violations of the laws or customs of war; the murder, ill treatment, or deportation to slave labor or for any other purpose of the civilian population in occupied territory; the murder or ill treatment of prisoners of war or persons on the seas; killing of hostages; torture or inhuman treatment, including biological experiments; plunder of public or private property; wanton destruction of cities, towns or villages; and devastation not justified by military necessity; rape, sexual slavery, forced pregnancy or any other form of sexual violence; conscripting or enlisting children under the age of 15 years into armed forces or groups or using them to participate actively in hostilities.

4. While war crimes have been prohibited for centuries, until the 20th century there were few international venues to prosecute such acts. The atrocities of World War II changed the view of war crimes and led to the Nuremberg trials. This series of military tribunals held by the Allied forces indicted 24 major political and military leaders of Nazi Germany. An additional 185 defendants, representing many sectors of German society, were also tried before the United States Nuremberg Military Tribunals in a series of 12 trials known as “Subsequent Nuremberg Proceedings.”

5. In 2002, the Rome Statute created the International Criminal Court (ICC), a permanent institution that has power to exercise its jurisdiction over persons for the most serious crimes of international concern. The ICC has jurisdiction over four main crimes, including war crimes. Currently, 123 states have ratified or acceded to the Rome Statute. The United States signed the treaty but has refused ratification.

6. According to the United Nations, war crimes contain two main elements: a contextual element (i.e., the conduct took place in the context of and was associated with an international/non-international armed conflict) and a mental element (i.e., intent and knowledge both with regards to the individual act and the contextual element). These two elements are what often distinguishes war crimes from genocide or general crimes against humanity.

7. In 1996, President Bill Clinton signed the War Crimes Act of 1996. The act amended federal law to make it possible to carry out the international obligations of the United States under the Geneva Conventions to provide criminal penalties for certain war crimes. According to the law, “Whoever, whether inside or outside the United States, commits a grave breach of the Geneva Conventions, in any of the circumstances described in subsection (b), shall be fined under this title or imprisoned for life or any term of years, or both, and if death results to the victim, shall also be subject to the penalty of death.”

8. The most famous war crimes trial of an American was for the My Lai Massacre during the Vietnam War. On March 16, 1968, a group of U.S. Army soldiers killed between 347 and 504 unarmed Vietnamese civilians—including women, children, and infants. Although 26 soldiers were charged with criminal offenses, the only one convicted was a platoon leader, Lieutenant William Calley Jr. Found guilty of killing 22 villagers, Calley was originally given a life sentence but served only three and a half years under house arrest.

9. To date, there have been nine present and former heads of state who have been charged with war crimes: Karl Dönitz (who briefly succeeded Adolf Hitler as the head of state of Germany); Hideki Tōjō (Prime Minister of Japan during much of World War II); Kuniaki Koiso (Prime Minister of Japan during the latter years of World War II); Slobodan Milošević (former president of Serbia); Charles G. Taylor (former president of Liberia); Omar al-Bashir (current president of Sudan); Muammar Gaddafi (former ruler of Libya); Franjo Tuđman (former president of Croatia); and Andrej Plenkovic (former prime minister of Croatia).

10. The most recent convictions for war crimes occurred earlier this week when the U.N. International Criminal Tribunal upheld the convictions of six Bosnian Croat military and political leaders, including Franjo Tuđman, a former president of Croatia, and Andrej Plenkovic, a former prime minister of Croatia. After judges confirmed his 20-year sentence, the retired Croation general Slobodan Praljak drank a cup of poison and died before he could be taken to the hospital.

Joe Carter is an adjunct professor of journalism at Patrick Henry College, an editor for several organizations, and the author of the NIV Lifehacks Bible.

Photo Credit: Skull of a victim of the Srebrenica massacre in July 1995, with a bullet entry point in the cranium. Exhumed mass grave outside the village of Potocari, Bosnia and Herzegovina. July 2007. Photo by Adam Jones, via Wikimedia Commons.