This Wall Street Journal editorial explains brilliantly the reasons why Obama's terrible decision to implement tariffs on Chinese tyres matters so much, how it represents a colossal step in the wrong direction.

Why, for instance, the ruling from Obama in favour of the tyre tariffs matters:

So some leadership from Mr. Obama to discourage this creeping protectionism would help. The President's apologists might argue his hands are tied in these steel cases, and that's true up to a point. Unlike the legal provision that gave the White House total discretion on tires, the law on antidumping and countervailing-duty claims leaves less leeway to the President's political appointees in the Commerce Department to interfere.

But precisely because Mr. Obama has few chances to intervene directly, this kind of case is where political leadership on trade counts the most. Forget about persuading Capitol Hill to adjust the laws governing these cases to make them harder to file or to minimize the resulting duties. Or any effort to fix a glaring inconsistency in U.S. trade law that treats China as a market economy in countervailing duty cases at the same time it's a nonmarket economy in antidumping cases (a novelty unleashed by Mr. Bush in 2007). Mr. Obama hasn't even made the kind of strong pro-trade statements that might just shame some companies into not filing cases like this.

Why tariffs, or other forms of barriers to trade, cause so much damage:

Steel duties are dangerous for the U.S. economy, as previous Administrations have learned to their chagrin. In the extreme, President Bush's 2002 broad-based steel tariffs of up to 30% on $8 billion in imports cost Americans 200,000 jobs and $4 billion in lost wages, by one count.

And, finally, a failure of Obama to do more to stand up to the protectionists - at home or internationally:

While previous Administrations have imposed their share of antidumping duties, that was in the context of their broader pushes for liberalization like the Uruguay Round, Nafta or Doha. In contrast, the Obama Administration talks a lot about the virtues of trade enforcement to the exclusion of any other trade policy. The steel cases show the costs of that approach.

"We need to guard against protectionism around the world," U.S. Trade Representative Ron Kirk said this week. For that to mean something, Mr. Obama himself needs to take up the free-trade banner, and much more forcefully. A good place to start will be at next week's Group of 20 summit in Pittsburgh, the former heart of American steel country.