I'm going to go with the most flagrantly obvious one. Um...the war on drugs... Clearly Unconstitutional and a massive violation of our privacy. Look at the entire way it's fought and there is zero constitutional authority for what is done in the name of a war that doesn't even work.
As much as I DETEST the war on drugs, the constitutional authority for it is clear in the authorization of Congress to regulate interstate commerce. That includes banning commerce in certain products. It's miserably stupid, counterproductive, fails any reasonable cost-benefit analysis, and should be abandoned the day before yesterday, but it's not unconstitutional.
But you ignored the major part of my argument that the Federal government only has power to defend the United States and clearly war after war were not doing that.
That's just not the case. What are you referring to here, the provision in Article I, Section 8, clause 1 that limits taxing/spending to providing for the common defense and general welfare, and makes no provision for spending for offense? But there's a separate authorization for Congress to create an army and navy, and no restrictions on how it's used by the executive except for that "declare war" thingy. There just isn't anything in the Constitution that forbids the waging of aggressive war by the United States. Maybe there should be, but there isn't.
At least since you don't support Constitutional limits on things you support, you're trying to be even handed with things you don't. But the better answer is that if you want it and it's not in the Constitution, change the Constitution via the way it was written to be changed, which is 2/3, 2/3 and 3/4, not 5/9 or a vote of 535 people.
Look, I keep saying this but apparently it's falling on deaf ears. I'm not talking about what the Constitution SHOULD be, I'm talking about what it IS. And it just plain ISN'T a document that sets up a limited government along libertarian lines. It sets up a hugely powerful central government. Why do you think it was so controversial at the time? Sure, it's a government of enumerated powers, but those powers (two of them in particular) are so broad that this almost doesn't matter. Just to cite one obvious example, look at the taxation clause of Article I:8.
"The Congress shall have Power To lay and collect Taxes, Duties, Imposts and Excises, to pay the Debts and provide for the common Defence and general Welfare of the United States; but all Duties, Imposts and Excises shall be uniform throughout the United States;"
What limits does this place on taxation? Well, all taxes have to be for the common defense and/or general welfare of the U.S., but those are pretty vague phrases that can mean damned near anything. And all of those three specific types of taxes have to be uniform, e.g. the government can't impose a duty on goods coming into New York without imposing the same duty on goods coming into Los Angeles. Otherwise, there are no limits at all! As I noted elsewhere, there is nothing in the Constitution that forbids the government from imposing a 100% income tax on everybody. (Something in common sense, yes, but in the Constitution, no.)
Now add in the regulation of commerce clause, and -- to pose another extreme hypothetical -- the government could convert us to a full-on socialist economy. How? By levying taxes on corporations equal to their stock value and earmarking the revenues to purchase all of the companies so taxed (or just allowing the tax to be paid in stock rather than money). (The government can't just nationalize the companies without compensation because of the 5th Amendment, but this procedure would amount to the same thing.)
This is what I mean when I speak of the Founding Fathers as not being all liberals, all conservatives, or all libertarians (at that time liberal and libertarian were identical). A lot of this language I'm convinced came from Hamilton. He was definitely a strong-government advocate as we can see from the suggestions of his that didn't make it into the final document, like a lifetime presidency with an override-proof veto.
Anyway, the Constitution doesn't create a government of unlimited powers, but it does create one of very broad powers. To this date, the government has never come close to exerting the full breadth of authority that the document grants it, even though it has expanded quite a lot over the time of its existence. Really, if you want to complain about big government, certain of the Founding Fathers are the ones you should ***** at.