The Netherlands have a decentralized governmental system. Besides the national government, there are governmental bodies on a regional level (the 12 provinces) and on a local level (the municipalities, around 550, an number that is gradually decreasing because of a continuing municipal regrouping). These are the only governmental bodies with territorial responsibilities. All three governmental bodies have powers derived from the constitution. Therefore, they have a certain autonomy. But the provinces and the municipalities are not allowed to act in ways that do not match with the policy specified by the national government. In general, a higher authority can exercise supervision over a lower authority, to ensure that it does nothing inconsistent with the policy being pursued by the higher. A lower authority cannot choose whether or not to execute a higher authority’s policy, but it is free to interpret it within specified limits. If the local authority chooses to use its autonomous powers to pursue a policy that does not derive from a higher authority, there is talk of complementary government.