Palestine asked to join the International Criminal Court in 2009. Its request was rejected three years later on the basis that it was not considered a state by the United Nations. However, in November 2012, Palestine was recognised as an observer state at the United Nations, so it reapplied to become a state party to the ICC.
Now that it is party to the ICC, it will ask the ICC to consider two cases of war crimes since June 2014: the illegal construction of settlements by Israel in the West Bank, and the military action of Israel in the conflict in Gaza in spring 2014.
If the ICC decides to investigate the situation in Gaza in spring 2014, it is likely to look at crimes committed by both Israelis and Palestinians. According to Amnesty International:
The scale of destruction, death and injury wrought by Israeli forces in the Gaza Strip during the 50-day conflict in 2014 was unprecedented. According to UN figures, more than 2,250 people were killed in the Gaza Strip, including over 530 children and some 1,000 other civilians, while over 11,000 people were injured. An estimated 117,000 people were left homeless. Six months after the ceasefire, reconstruction has barely begun, due to Israel's continuing restrictions on imports and unfulfilled funding pledges. Palestinian armed groups fired thousands of indiscriminate rockets and mortars into civilian areas of Israel during the conflict; these killed six Israeli civilians, including a child, injured dozens, and damaged civilian property in Israel. Sixty-six Israeli soldiers were also killed.