Sometimes the most difficult task in constitutional reform is building consensus about the need for reform, the type of reform, and the process for achieving reform. In some situations the need for reform is obvious to all—for example at the moment of independence, or after a revolution (e.g., as in Spain, Hungary, and Poland). Often reform is resisted by those in power, such as Marcos in the Philippines and Moi in Kenya from 1991 to 2000—they took office and attained power through the existing constitution. Sometimes a minority, excluded from government, wants reform but the majority resists it (if necessary by force of arms), as in Sri Lanka from the 1980s to 2009. In these situations the agreement to reform (or talk about reform) comes only after an intense conflict in which many lives may have been lost (as in South Africa, Sudan, and parts of India). These days it is not unusual that an agreement to consider or negotiate reform is the result of external pressure (as in Afghanistan, Cambodia, Kenya, Sudan, and Timor-Leste).
The agreement could be no more substantial than a decision to meet to consider reform, or it could be quite wide ranging, touching the areas of reform, the principles underlying reform, and the institutions for negotiation and the making and approving of reform measures. In conflict or postconflict situations, parties are unlikely to agree to talk about reform unless they feel that their critical interests will be protected. Thus, a prior agreement or understanding about the safeguarding of these interests, and about the fundamental constitutional principles to be incorporated in the final constitution, is often a precondition for negotiations. If the international community becomes engaged, then the incorporation of human rights as expressed in international treaties is likely to be mandatory.