Canadian constitutional law has something called the 'living tree doctrine', which states that the constitution can grow and evolve over time, being reinterpreted in new contexts. To push the metaphor a bit further, I'd point out that a living tree is considerably more resilient than a dead tree, and is likely to adapt to conditions which might otherwise destroy it.
I don't think anyone can seriously claim that the commerce clause of the US constitution was intended to grant the vast powers which it has been used to uphold; but because the US constitution is -- theoretically -- not subject to growth and reinterpretation the way that the Canadian or British constitutions are, a legal fiction has been adopted instead.
If the commerce clause had been interpreted within the context of the Canadian or British constitutions, it would probably have been handled as "we're going to read one new power into this" on a number of occasions, rather than the "yes, this clause gives you the power to do everything" which seems to have occurred in the US.
I find it extremely disingenuous to say that because the Canadian (or British)
Constitution can easily be re-interpreted in different contexts, that it will
always be interpreted in 'the correct way.' You seem to be pointing to examples
of the US Constitution being interpreted poorly, making the implication that a
'dead tree' constitution can only be interpreted poorly, and a 'living tree'
constitution can only be interpreted in a good way.
A constitution that can be easily re-interpreted may allow for your government
to 'turn on a dime,' but it makes no claims to whether your government is
turning in a good or bad direction.
As to the US Constitution:
* The US Constitution can be re-interpreted by the US Supreme Court through the
setting of legal precedent.
* The US Constitution can be amended by Congress. (Prohibition was a
Constitutional Amendment).
* The current interpretation of the commerce clause could be overturned by the
US Supreme Court should a case come before them, and the make-up of the
justices leans towards overturning the current state of affairs.
There are other basic protections built in to attempt to prevent turning on a dime in a bad direction, as decided by the legislative and executive branches. Since the Court has no enforcement powers of their own, an unpopular turn away from the appearance of consistency could result in a toothless ruling and a constitutional crisis.
Let's use your example, the Court suddenly ruling to overturn the current interpretation of the Commerce Clause. Assuming "current" means "1964 and later", this would also overturn the Civil Rights Act. The CRA was based upon the Commerce Clause, and Heart of Atlanta Motel v. United States (1964) upheld its broad definition of interstate commerce [1].
I would have a hard time believing Congress would follow along with a ruling that simultaneously overturned a hugely popular law and decreased their powers. (However, I am aware that there have been a few rulings that might be counterarguments.)
[1]Epstien, Walker. Constitutional Law for a Changing America: Rights, Liberties, and Justice 5th ed. Page 658.
Amended by Congress with the approval of the States. It's a slight difference. In the grand scheme of things like checks and balances, it matters, but in the real-world Congress is the only one that has the power to start the process. The States themselves can't float a Constitutional amendment so far as I understand it.
In fact they can, but it has never happened. The relevant text is here: http://www.usconstitution.net/const.html#Article5. The basic idea is that 2/3 of the state legislatures must call a Constitutional Convention, where the Amendment(s) will be proposed and sent to the states for ratification.
The Congress shall have Power...
To regulate Commerce with foreign Nations, and among the several States, and with the Indian tribes;"
It's not really a matter of living versus dead trees. The US judicial system has just plainly ignored the "among the several States" caveat for the last 100 years. I'm not advocating either side of this example, by how does growing and consuming marijuana on your own property fall under regulated commerce "among the several States?" I understand it was originally banned using taxation powers (i.e. charge a stamp tax on it, but don't sell the stamps), but that pretext seems to have now been dropped.
Without endorsement, as a result of reading the recent Virginia decision on the constitutionality of the health care purchase mandate (which I mention without endorsement of either side), it has been ruled by the Supreme Court in Wickard v. Filburn (1942) [1] that the US government can regulate the act of a farmer growing wheat to feed his own chickens on the grounds that had the farmer not grown that wheat, he would have then participated in the national wheat market that Congress could regulate, that his failure to purchase wheat on this market therefore affected the market by his absence, and thereby Congress can regulate his action in accordance with the Commerce Clause.
Again, I mention this without endorsement of either side; I mention this just because I only recently learned about this myself.
That kind of ruling just turns my stomach. The court used a an enumerated power--that was primarily intended to prevent tariffs being erected between the states--to effectively remove all limits to federal power. Gonzales v. Raich (2005)[1] is analogous to the Wickard v. Filburn case that you cite. In his dissent, Justice Thomas said the following:
If the Federal Government can regulate growing a half-dozen cannabis plants for personal
consumption (not because it is interstate commerce, but because it is inextricably bound up
with interstate commerce), then Congress' Article I powers -- as expanded by the Necessary
and Proper Clause -- have no meaningful limits. Whether Congress aims at the possession of
drugs, guns, or any number of other items, it may continue to "appropria[te] state police
powers under the guise of regulating commerce."
> To push the metaphor a bit further, I'd point out that a living tree is considerably more resilient than a dead tree, and is likely to adapt to conditions which might otherwise destroy it.
Trees that grow in unexpected ways get cut down.
Explicit amendments are far more legitimate.
The US has amended its constitution several times. If something really is a good idea, the amendment process is no real obstacle.
I don't think anyone can seriously claim that the commerce clause of the US constitution was intended to grant the vast powers which it has been used to uphold; but because the US constitution is -- theoretically -- not subject to growth and reinterpretation the way that the Canadian or British constitutions are, a legal fiction has been adopted instead.
If the commerce clause had been interpreted within the context of the Canadian or British constitutions, it would probably have been handled as "we're going to read one new power into this" on a number of occasions, rather than the "yes, this clause gives you the power to do everything" which seems to have occurred in the US.