Well, it varies between countries.
Very often, you do find an explicit requirement to conduct a census; the requirement is laid down in the law. More generally, of course, a minister can issue the request to compile some form of information or statistics that he or she may need. What is not normally the case is that the minister would exert some judgment about how exactly this information should be compiled, and would interfere in terms of the methods that are being used.
You see in some OECD countries you have censuses that are conducted purely with administrative records. Denmark is—