Randy Barnett has come up with one: the Bill of Federalism. This is a set of constitutional amendments to the US Constitution intended to restore it to its rightful level of authority. Most of them sound like a good idea. Here's my take on them.
The Ten Amendments of The Bill of Federalism
Amendment 1 [Restrictions on Tax Powers of Congress] (Removing the income tax and replacing it with a sales tax)
I'm not opposed to the income tax in principle but what we've got now is encrusted with too many complications for anyone to understand it, even a Secretary of the Treasury. So sure, let's replace it with something else. Then when the sales/VAT/whatever tax has become unmanageable from decades of Congressional twiddling let's abolish that and move on to something else. Give the Georgists a chance to implement their taxing land only scheme, maybe.
Amendment 2 [Limits of Commerce Power]
"And this time we mean it." Restoring the 10th Amendment of the Bill of Rights by limiting the scope of the Interstate Commerce clause. Wouldn't eliminate laws so much as create a "didn't cross the line" defense in Federal courts. A useful check on the power of Congress if it works.
Amendment 3 [Unfunded Mandates and Conditions on Spending]
Congress shouldn't be able to make a state government raise the taxes to pay what they want done. Responsibility should stay with authority, not get delegated away. Likewise, bribing states into imposing laws is a bad way to create policy.
Amendment 4 [No Abuse of the Treaty Power] (Treaties don't give Congress additional legislative authority, nor do they have a domestic effect without enforcing legislation)
This is probably necessary given some of the attempts to restrict individual rights through international law.
Amendment 5 [Freedom of Political Speech and Press] (removing restrictions on campaign contributions and advocating candidates)
The various "campaign finance" reforms have quickly become another set of tools to protect incumbents. Replacing the current political establishment will only happen if we let people support candidates as much as they can.
Amendment 6 [Power of States to Check Federal Power] (A federal law could be repealed by 2/3s of the states passing resolutions)
A useful way to keep the President and Congress from colluding in something that benefits them but not the rest of the country. Actually implementing it would require getting several thousand legislators to vote for identical resolutions, something that probably would never happen. But once a dozen or two states passed one Congress would probably be taking action to amend whatever they were objecting to.
Amendment 7 [Term Limits for Congress]
There's 535 arguments in favor of this. But I don't think "the current crop is all stinkers" is a good reason to change the rules. This shifts power away from the elected legislators toward the bureaucracy. It would eliminate the motive for a lot of the current corruption in the budget. If they can't get reelected there's less need to bribe their constituents and contributors.
AMBIVALENT, LEANING FOR
Amendment 8 [Balanced Budget Line Item Veto] (The President would have a line item veto in years when the federal debt had increased)
This is a lovely piece of systems design. Balanced budget rules always break down over how to enforce them while leaving the capability to handle an emergency. Line item veto debates focus on how the President could abuse the power. Barnett's proposal lets Congress decide which set of rules should be in operation at any time. If they splurge on pork the President can pull out the red pen. If they keep the budget in the black they can spend it however they please. If a world war breaks out they can both cooperate to deal with the crisis. Lovely.
FOR, HELL YES
Amendment 9 [The Rights Retained by the People]
"And this time we mean it." Provides the opportunity to introduce a 9th Amendment defense in any legal case. Specifically mentioning some rights in this amendment could have a mixed impact--enumerating additional rights protects them but gives the impression that the "unenumerated rights" that didn't make the list are less important. So it still has some of the weaknesses of the original 9th, but would make a lot of judges pay attention to it for a generation or two.
Amendment 10 [Neither Foreign Law nor American Judges May Alter the Meaning of Constitution]
I don't think there's a single serving judge who'd deny acting according to this already. No law can control how a judge will read it. Still, passing this amendment would serve to put judges on notice that they're expected to adhere to originalism. That would probably save a few from the temptation to interpret broadly.
While we're editing the Constitution, I can think of a few other changes I'd like to make. Deleting the militia clause from the 2nd Amendment would save some arguments. The 5th should be clarified to make it clear "public use" does not mean "giving it to anyone who'll pay more taxes on it." I'd like to see one house be proportional representation but that's not practical unless we're starting from scratch. The biggest change I'd want is banning gerrymandering.
A big part of why Congress is so static nowadays is that reapportionment lets the politicians pick their voters instead of the other way around. When Congressmen owe their election to pleasing the hard core party members who vote in primaries they keep going to the extreme and ignoring what the majority in the middle wants. An anti-gerrymandering amendment would make for more competitive House races and give us a crop of more moderate winners. "Non-partisan" commissions have been proposed in place of having the legislatures draw the lines. That'd be an improvement but still leaves the problem of having "incumbent protection" gerrymanders instead of ones designed to favor a single party. So let's try this:
Amendment N: Congressional Redistricting.That forces the districts to be compact and similar in size. We'd want to do a bunch of tests to make sure this holds up. A contest offering a prize to whoever produces the most gerrymandered map meeting the rule should find any loopholes.
After each census revised congressional districts shall be drawn by each state. Each member of the state legislature may propose a redistricting plan. Plans with a standard deviation of the number of eligible voters in the districts greater than 2% shall not be considered. The eligible plans shall be evaluated by summing the length of each district's perimeter. The one with the shortest total length shall become the new district map.