Treason is when a soldier or civilian of a country betrays his or her country by supporting the enemy in some way or another. Treason is prohibited by the law, 18 U.S. Code Chapter 115 and this law was especially relevant during the cold war because both the USSR and the US were using spy's against each other attempting to give their nation an advantage in the Cold War.
In 1948 the UN made a sub council to address war crimes such as torture and have the committee members specialize in prosecuting people that use torture. Torture was used as a method to receive valuable information from an enemy soldier or to punish a soldier for his actions. Often times torture would be just physical pain, but psychological torture would be used to wear down the hostage mentally in a hope to receive information. With its ban, many soldiers that were POWs could receive better treatment and come back from the war without additional battle scars.
This code of ethics agreed upon by the members of the nuclear community especially, establishes more protection for people stuck in a war-zone. However, more importantly in 1996 it was used as the law restricting countries from using nuclear weapons in wartime and establishes harsh punishments for any country attempting to use nukes against their enemies.
Despite many nations throughout the years accepting common agreement about what they shouldn't do, it wasn't until the amendment of the Geneva Convention in 1949 that rules were set in stone. With almost every country in the world agreeing to these rules, the establishment of these regulations have saved countless lives and ensured a more clean war.