On the eve of the G20 summit in London, France’s Nicolas Sarkozy and Germany’s Angela Merkel, in a joint conference at a London hotel, said an agreement on April 2nd must include tougher financial regulations. The buzz preceding this G20 conference has for weeks now indicated the leading themes-and worries-that will shape its discussion. Chief among them is creeping protectionism.

When the group met last November leaders pledged to avoid enacting protectionism measures in their countries. However, since their pledge in November, 17 of the 20 members have enacted 47 trade-restricting measures (according to a recent World Bank report). From export subsidies to trade restrictions and bans on foreign products, protectionism is the order of the day when thing get rough in domestic economies and free trade is likely to be the first victim, with prosperity a very close second.

Protectionism is a troubling but not so unexpected a derivative of financial crisis. When things get rough, the easiest route is to protect the home base. However, protecting the home base can cause plenty of other issues that can exacerbate the global financial problems rather than fixing them.

In continental America protectionism can cause lot of damage and is best illustrated in the tit-for-tat spat between the U.S. and Mexico over trucking. Mexico has raised tariffs on 89 American products worth $2.4 billion in annual trade in retaliation for a U.S. decision to cancel a program that gave Mexican truckers access to U.S. highways. American fruit, wine, and washing machines will be among the goods affected.

Europe could do a lot worse. Currently the European Union is struggling with an imperfect union, one that has its members disengaged and disagreeing on basic tenets of how the Union should work. Protectionism measures can have a debilitating effect on EU economies and such measures will undo much of the hard work the European Union has done in the past couple of decades.

The leaders of the G20 nations have feebly respected their pledge of November to avoid turning inwards in fighting the economic crisis. Since then, world commerce has plummeted in a way unseen since the Great Depression.

“We’re playing with fire,” said Jagdish Bhagwati, an economist at Columbia University to the Associated Press. “The system was designed to avoid the free-for-all wrestling of the 1930s. If the U.S. and France start saying, ‘This is legal so I am going to do it,’ everyone else will start to play that game.”

But much of the comments so far have appeared to be diplomatic posturing as leaders put the finishing touches on a communiqué set for release on April 2nd.  The communiqué is supposed include a laundry list of carefully worded prescriptions that leaders have already agreed to beforehand. But will these prescriptions adequately address protectionism? It remains to be seen.