Let me try this from another angle to avoid allowing you to take this discussion into la la land. Here is Judge Robert's opinion on the case. http://www.supremecourt.gov/opinions/12pdf/12-96_6k47.pdf
There are two specific points made to justify the decision.
1. State voting law changes fall under the protection of the 10th amendment, which states that "powers not delegated to the United States by the Constitution, nor prohibited by it to the State, are reserved to the State respectively, or to the people".
2. There is a “fundamental principle of equal sovereignty” among the states that the Voting Rights Act violates by only subjecting southern states to comply with preclearance mandates.
As to the first point, the Constitution is pretty straight forward. It says that powers not granted to the Federal Government by the Constitution are reserved for the states. Problem with the decision, however, is that overseeing that the right to vote is not denied or abridged is explicitly granted to Congress by the 14th and 15th amendments. Because this power is indeed granted to Congress by the Constitution, then Congress is not violating the Constitution by enacting laws that use this power.
As to the second point, there is no "principle of equal sovereignty" expressed in the Constitution, as noted by that Stanford professor that you know nothing about yet chose to characterize as a partisan (who just so happened to be a retired appellate court judge appointed to the position by George W. Bush, who was also on the short-list of candidates for the SC seat that was eventually given to Samuel Alito). Ruth Bader-Ginsberg's dissent touched upon this as well. The Court decided to deny Congress a power granted to them by the Constitution by citing that it violated a principle that isn't even in the Constitution.
Care to talk about the opinion, or are you happy with just trying to constantly change the subject?