The Treaty of Treason is a treaty created by the Capitol to ensure peace after the districts were defeated during the first rebellion, referred to as the Dark Days. As well as implementing laws to keep peace in the districts, it detailed the first Hunger Games to remind the districts that the Dark Days must never be repeated. The mayor of each district is required to read the treaty during each year's reaping.
In The Hunger Games film, the treaty is incorrectly referred to as "the Treaty of the Treason". An excerpt from the treaty is shown. It states, "In penance for their uprising, each district shall offer up a male and a female between the ages of 12 and 18 at a public "reaping". These tributes shall be delivered to the custody of the Capitol. And then transferred to a public arena, where they will fight to the death until a lone victor remains. Henceforth and forevermore this pageant shall be known as The Hunger Games."