You think we live under a Constitution these days? The Feds are lawless, corrupt, and out of control of the written Constitution.
Yeah, actually, I think we still live under the Constitution. No one has scrapped it, we've still got the Supreme Court, and we still have the three branches of government, we're still electing representatives (even if they aren't always the ones that we want, but we do get ours in there, too), and the laws are still made and prosecuted and people are imprisoned, due process is still being done, and all those other things that have been done in the past are still being done now.
What you're talking about is that the "policies" and the "legislation" that is being voted on and passed is not what we want to see... but that's a matter of politics.
Now, the fact of whether the Constitution is still in effect is going to be see by the process that is used to challenge "Obamacare" (for one example). If it gets challenged and a case is brought forth and the case is heard, and it makes it up to the Supreme Court and the Supreme Court hears it based upon the Constitution -- then yes... the Constitution is still being used ...
Our legislators cannot specify what part of the existing Constitution permits them to mandate the people buy health insurance, what part of the Constitution permits them to declare CO2 a pollutant, what part of the Constitution permits them to convey property from one citizen to another with no limits, or to distribute private assets to their whim. They are totally out of the bounds of out written Constitution - and are absolutely lawless.