The first part about the states is true. The second part about the Feds really depends on the issue. SCOTUS has allowed them to overreach on many things based on the Commerce Clause mostly. I personally think that the reading has been overly expansive, but their position is at least nominally based on the Constitution. It is not an interpretation that I agree with, but they aren't just making it up out of nowhere. And, if you read things like the Federalist Papers and other documents written by the founders, you will find that there was not even total agreement about what the Constitution meant or should mean. Moreover, many issues were just not thought of or discussed. So some level of interpretation is necessary because of those disagreements among the founders and the fact that no document can be totally comprehensive. Now, I tend to read the whole document in the light of the 9th Amendment, but those who disagree, at least in the legal field, are usually having a legitimate academic discussion rather than being part of any systematic effort to grow the power of the Federal Government.