Here’s what’s at stake at the Supreme Court this week as it considers challenges to the Patient Protection and Affordable Care Act (a.k.a. Obamacare): whether we will move from the American model of democracy toward a British one.

Schoolchildren learn that Americans fought for independence to secure democracy and liberty.  “Taxation without representation” was the phrase revolutionary Americans used as shorthand to refer to the un-democratic  and anti-freedom elements of the British system, at least as it applied to colonists in 1776.  But we didn’t flesh out our approach to liberty until we wrote our constitution in 1787,  when we established a system of government with three structural bulwarks against tyranny, including tyranny by the majority.

The first bulwark is the separation of power among the three branches of the federal government.  The second bulwark is federalism: power is divided between states and the national government, each with constitutional protections against losing autonomy to the other.   The third bulwark is embodied in the principle that the federal government is one of enumerated powers, meaning it has no power unless the Constitution says it does (in contrast to the states, which have all the powers governments anywhere might have except those the constitution denies to them, or gives to the federal government).

Under the American system, no one in the federal government can achieve the subjection of every aspect of human life to the government’s jurisdiction, so no one has much incentive to attempt it.  Much is left to individual choice. We are allowed to run our own lives.

In 1787, with no other functioning democracies to point to, it understandably appeared to the Founders that these structural protections were necessary to protect democracy and liberty.  For 150 years that consensus prevailed.

But by the 1930’s some Americans’ faith in limited government was eroding. Herbert Hoover strove to tame the intractable Depression using the tools of limited government. But he seemed to fail so badly that Congress embraced Roosevelt’s radical expansions of federal power in an effort to manage its way out of the mess.

Things went so far that in 1942 the Supreme Court ruled unanimously that Congress could prohibit a farmer from growing wheat on his own land for his own cattle. Wickard v. Fillburn, 317 U.S. 111 (1942).  The Court said its ruling was within the constitution’s express grant to Congress of power over interstate commerce, since Fillburn’s decision to produce his own wheat rather than buy wheat on the market undermined Congress’ policy objective of propping up the price of wheat.

Since then the Court has struggled with how to reconcile Fillburn’s expansive reading of Congressional commerce power with the fundamental principle of a national government vested with only limited powers.

Today’s oral argument in the Obamacare case focused on this question as it applies to the Affordable Care Act’s mandate that Americans must buy health insurance. This requirement goes beyond anything ever approved by the Court.  Even Wickard v. Fillburn didn’t require Mr. Fillburn to buy wheat. (Despite what Justices Kagan and Breyer said today, Fillburn had the option of slaughtering his cattle or selling them.)

If the Court upholds the health insurance mandate, will anything be left of the notion of limits on the powers of Congress, or of realms of human activity reserved to the sovereignty of the states?

Obamacare’s defenders argue that health insurance is a unique part of the American economy, since pretty much everyone relies on the health care industry at some point in life.  But pretty much everyone also relies on the clothing industry, and on agriculture, food processing, housing, transportation, and petroleum industries.  As Justice Scalia pointed out today, we all will need the services of the burial industry someday.  All these industries are interstate in reach, and thus all are subject to Congressional regulation. And it is possible in every one of them to imagine scenarios where Congress might conclude that making everyone buy some particular thing (or wear it, or eat it, or exercise with it, or be insured against its costs) would help achieve some conceivably legitimate policy objective.

This is why some see in the upcoming decision a watershed for liberty in America.  If the Supreme Court upholds Obamacare’s insurance mandate, it will pave the way for Congressional mandates in every conceivable area of life.  Congress could take it into its head to require everyone to buy a basket of tomatoes each September, to keep tomato farmers in business in the face of the annual gardeners’ tomato glut.

If the Court upholds Obamacare, it will have erased two of the bulwarks against totalitarianism — federalism and the notion of limited government — that distinguish America’s brand of democracy.

But the world is not the same now as it was in 1787. We are not the only democracy.  Among the many democracies around the world, few rely on constitutional restraints on legislative power.  And the leading un-American democracy on the planet may be Great Britain’s – our former oppressors, now our firmest, most reliable democratic ally!

They have no coherent written constitution in Britain. No legal restraint exists on Parliament’s power, and the British are completely frank about it. Parliament can legislate whatever it wants to. There are no states to impinge upon, and no constitutional declaration of individual rights to cite in opposition to Parliament’s plenary powers. Yet Britons enjoy as much democracy as we do, and about as much freedom.

One might question whether Congress, President and the Supreme Court should have the power to swap out the American system of limited government for the British model, changing by fiat basic structures of the American Constitution.  But will the world end if they do?  Won’t that just deposit us into the mainstream of Anglo-American democracy, back at the family table with the Mother Country and our Canadian, Australian, etc. siblings, where potentially all-powerful legislatures are  effectively restrained by only one thing: the desire to be re-elected?