§1. The alienation of goods whose value exceeds the defined minimum amount also requires the following: 1/ a just cause, such as urgent necessity, evident advantage, piety, charity, or some other grave pastoral reason; 2/ a written appraisal by experts of the asset to be alienated.
§2. Other precautions prescribed by legitimate authority are also to be observed to avoid harm to the Church.
Source: Code of Canon Law (Vatican.va)