Grave Breaches (of the Geneva Conventions)
Not all violations of the treaty are treated equally. The most serious crimes are termed grave breaches, and provide a legal definition of a war crime. Grave breaches of the Third and Fourth Geneva Conventions include the following acts if committed against a person protected by the convention:

willful killing, torture or inhuman treatment, including biological experiments
willfully causing great suffering or serious injury to body or health
compelling one to serve in the forces of a hostile power
willfully depriving one of the right to a fair trial. (BINGO)
Also considered grave breaches of the Fourth Geneva Convention are the following:

taking of hostages
extensive destruction and appropriation of property not justified by military necessity and carried out unlawfully and wantonly
unlawful deportation, transfer, or confinement.[8]
Nations who are party to these treaties must enact and enforce legislation penalizing any of these crimes.[9] Nations are also obligated to search for persons alleged to commit these crimes, or ordered them to be committed, and to bring them to trial regardless of their nationality and regardless of the place where the crimes took place.

The principle of universal jurisdiction also applies to the enforcement of grave breaches. Toward this end, the International Criminal Tribunal for Rwanda and the International Criminal Tribunal for the former Yugoslavia were established by the United Nations to prosecute alleged violations.