The problem with judging the constitutionality of most issues boils down to this: Are you judging based on the Constitution as adopted or the Constitution as one side or another wishes it to be?
As adopted, if you want to judge the constitutionality of an act by looking at Article I, Section 8. If it is listed there, then it is constitutional. If not, it is not constitutional. On the other hand, since about 1790, there have been those who judge the constitutionality of an act by "I want X to be constitutional, therefore it is," or "if you torture the language enough, you can see a penumbra that covers Y," or "if I had been in Philadelphia, I would have included Z, therefore Z is constitutional."
The latter method has held sway for a long time, but the former still asserts itself from time to time.