This task is about reading the given passage and construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) its answer is a continuous text span from the paragraph. Avoid creating questions that (i) can be answered correctly without actually understanding the paragraph and (ii) uses same words or phrases given in the passage.
Q: Federations often employ the paradox of being a union of states, while still being states (or having aspects of statehood) in themselves. For example, James Madison (author of the US Constitution) wrote in Federalist Paper No. 39 that the US Constitution "is in strictness neither a national nor a federal constitution; but a composition of both. In its foundation, it is federal, not national; in the sources from which the ordinary powers of the Government are drawn, it is partly federal, and partly national..." This stems from the fact that states in the US maintain all sovereignty that they do not yield to the federation by their own consent. This was reaffirmed by the Tenth Amendment to the United States Constitution, which reserves all powers and rights that are not delegated to the Federal Government as left to the States and to the people.
A:
What does federations often employ?