LONDON -- Former Prime Minister Margaret Thatcher once famously described -- or is alleged to have described -- the Japanese language as an unfair obstacle to trade. How, she is said to have demanded, could foreign suppliers possibly penetrate the rich Japanese market when it was protected by an impenetrable language barrier?

True or false, the story illustrates the absurdity of carrying the principle of trade liberalization to extremes, where every difference, cultural, historical or natural, becomes an "unfair" restraint on free trade, and where trade negotiators find themselves dragged into the most intimate nooks and crannies of every nation-state in their zeal to hunt out practices that might give the slightest trade advantage to one country.

Once found, goes the doctrine, any such advantage must be ironed out so that the "playing field" of world trade can be well and truly level. If workers get longer holidays in one country, then the same must apply to all. If taxes are notably lower in one economy, then this is unfair and they must be raised. Every kind of subsidy, direct or indirect, must be exposed. Nothing short of that will do.