In ordinary circumstances, constitutions are changed according to the process for constitutional amendment set out in the existing constitution. There are circumstances, however, in which it is not possible to follow the process set out in the existing constitution for example, in some post-conflict countries or where the established process is deemed inadequate. In such cases a new process or adjustments to the existing process are needed. Usually, the new process or adjustments are established legally, for example, by amendments to the existing constitution, or through a presidential decree, a law adopted by a legislature, or a peace agreement.