Cika wannan jumla: An fara tattaunawa don sauya tsarin EU a shekara ta 2001, wanda ya haifar da farko a cikin yarjejeniyar da aka tsara don kafa Tsarin Mulki na Turai, wanda zai soke yarjejeniyar Turai da ke da ita kuma ya maye gurbin su da "kundin tsarin mulki". Kodayake yawancin ƙasashe membobin sun amince da shi, an yi watsi da shi bayan an ƙi shi da kashi 55% na masu jefa ƙuri'a na Faransa a ranar 29 ga Mayu 2005 sannan kuma da kashi 61% na masu jefa ƙuri'a na Dutch a ranar 1 ga Yuni 2005. Bayan "lokacin tunani", kasashe membobin sun amince maimakon haka don kiyaye yarjejeniyoyin da ke akwai da kuma gyara su, don kawo doka da dama daga cikin gyare-gyaren da aka tsara a cikin tsarin mulkin da aka watsar. An shirya yarjejeniyar "gyare-gyare" mai gyarawa kuma an sanya hannu a Lisbon a 2007. Da farko an yi niyyar cewa dukkan kasashe membobin za su amince da shi a karshen shekara ta 2008. Wannan jadawalin bai yi nasara ba, musamman saboda ƙin amincewa da yarjejeniyar a watan Yunin 2008 da masu zaɓe na Irish suka yi, shawarar da aka juyar da ita a cikin wata sanarwa.
kuri'ar raba gardama ta biyu a watan Oktobar 2009 bayan da Ireland ta samu wasu abubuwan da suka shafi yarjejeniyar.