It's supposed to be a trade dispute between the U.S. and China over solar cells. But that's not the real story. What's more interesting is the way in which the Commerce Department determines whether imports are being ''dumped'' in U.S. markets. The formula might be based on prices in countries that have little or nothing to do with the matter at hand. It all comes down to whether or not the exporting nation in question is considered a ''market economy.'' And that decision is often more political than economic in nature, according to attorney William Perry, a partner in the trial department of Dorsey Whitney. He talks about the trade tensions that are simmering below the surface of relations between the U.S. and China, and offers his view on how the system should be improved.