Here's a good American Thinker post on the topic:
Who are the dastardly people who are now unhinging the left? They are the "Tenthers," those who believe the 10th Amendment -- reserving to the states and the people all powers not delegated to the federal government nor prohibited to the states -- isn't dead letter.
America is seeing a reawakening of interest in the Constitution, particularly how it should limit government power. People realize there is some foundational flaw with what's happening in Washington, and are tired of feeling helpless.
When the President exceeds his powers, what's to countermand him? When Congress succumbs to special interests, what can people do? When the courts create rights not found in the Constitution, and deny ones that exist, what's the solution? When all three branches abdicate their role of providing checks and balances, what's to stop the corruption that flows from authoritarianism?
Americans view the Bill of Rights with an almost sacrosanct reverence of what is good and special about America. The 10th Amendment is key to a structural view of limited federal government. People are now beginning to realize it as a vital Amendment. That it may be stale or dormant does not make it meaningless.
Liberals are just in their beginning phase of denigrating the conservatives and independents who now realize one reason why we have problems with abusive, corrupt government is that the 10th Amendment has been neglected. But what's to say one of the first ten Amendments is dead letter, as some on the left suggest for ideological reasons, yet be able to deny that weakening one Amendment weakens all of them? If that's the ideological debate in which the left wants to engage, I say, bring it on.
As with nearly any ideological debate involving the Constitution, the left engages in hypocrisy. As Michael Boldin of the Tenth Amendment Center does point out, some lefties have used 10th Amendment arguments for their causes.
By exposing their insufferable, intolerant, hypocritical ideology, the left continues to add numbers to the cause of freedom.
Leftists, if the Constitution is really null and void, then please just say so. We can all then proceed accordingly.