IAmA lawyer who teaches and practices the law of armed conflict. With the situation in Ukraine, there has been a lot of discussion about international law. Ask me anything!
The Law of War is often referred to as the law of armed conflict (LOAC), or international humanitarian law (IHL). They all refer to the same body of law. I will use IHL for uniformity. You will also often hear the Red Cross being part of this conversation. That's because the Red Cross is the unofficial arbiter of IHL. In the 1800s, a Swiss businessman named Henry Dunant had a vision for a group of neutral humanitarians to aid the victims of war on the battlefield, as well as a set of rules that would limit the effects of war on non-combatants. That group of humanitarians became the Red Cross, and the set of rules became the Geneva Conventions. So the two are intertwined, and the Red Cross is specifically mentioned in the Geneva Conventions. In fact, the Red Cross symbol (often confused as a medical symbol), is meant to identify non-combatant/civilian objects in conflict, including hospitals.
IHL is made up generally of international treaties, the big one being the Geneva Conventions. You will hear the International Criminal Court (ICC) mentioned plenty, and about signatories to the ICC. It's important to distinguish between the Geneva Conventions and the ICC, in that Geneva is the actual IHL, and the ICC is merely an enforcement mechanism. All countries are bound by IHL, its merely an issue of whether the ICC can enforce violations if a certain country is not a signatory. There are other mechanisms for enforcement, such as domestic enforcement (court martials), and the principle of universal jurisdiction, which is like, this crime is so heinous that any one can arrest you and prosecute you for it.
IHL is designed to be a practical body of law. In that it recognizes that civilians deaths can and will happen in war. So civilian casualties, however tragic, doesn't automatically mean war crime. IHL instead requires belligerents to follow basic principles of proportionality (minimize collateral damage), distinction (don't purposely attack civilians), humanity (don't be cruel), and necessity (attacks must be linked to a military objective.
You will also hear genocide, war crimes, and crimes against humanity being mentioned side by side. These are all legal terms. To over simplify: a war crime is a violation of IHL, and must occur in connection to a conflict. A crime against humanity is a systematic and large scale attack against a civilian population, which doesn't necessarily need to occur in a war. A genocide is trying to eliminate, in whole or in part, a population of a certain characteristic (e.g. religion), which also doesn't need to occur in war time. For example, Nazi Germany invading the Soviet Union and leveling entire cities to the ground is a war crime, at the same time, their extermination of Jewish people back in Germany is genocide, but that's not at all related to the invasion of the soviet union, and doesn't need to be.
That's all I have for the primer, happy to answer any specific questions you have!
EDIT 1: *** All of my opinions are my own ***
EDIT 2: Many of your questions, although great, are asking for political opinions. I'm going to stick to the law as much as I can, as I don't think my own political opinions are relevant or helpful here.
EDIT 3: Resources to learn more:
- Red Cross IHL Blog: (https://www.rulesofwar.org/),
- Youtube Channel with IHL lessons:(https://www.youtube.com/channel/UC14DKWvBZHosSdQw7xrJkBQ)
- If you are in High School/college, ways to get involved in IHL through your local IHL chapter: (https://www.redcross.org/humanityinwar/international-humanitarian-law-youth-action-campaign/get-involved.html)