What's the main power of the supreme court ?

The Supreme Court of the United States (SCOTUS) is the highest court in the country. The court has original jurisdiction over a small range of cases. However, its main power is to exercise ultimate appellate jurisdiction over all federal and state cases that present a question of constitutionality. This means that the Supreme Court rarely hears a case for the first time. Instead, it settles disputes over cases that have already been heard by lower courts. Moreover, its main duty is to examine the constitutionality (whether they match the constitution) of the laws or acts involved in these cases.

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an informal structure in a bureaucracy would be something like so-called "office politics". where there's a formal structure set up for the organization, but then an informal subculture as well that has a way of organizing the bureaucracy further. this can be positive because it sets up an added degree of organization, albeit informal, within the bureaucracy.