The United States tax code is so backward that billionaire investor Warren Buffett pays only 17 percent in income taxes, a rate even lower than that of his secretary. Or so he claims. While I have great respect for Mr. Buffett, and while I agree that our tax code could benefit from major adjustments, Mr. Buffett's statement is misleading. And he knows it. Even worse, when Mr. Buffett implies that wealthier Americans are under-taxed, it gives public officials cover to pursue disastrous policies such as Maryland's failed millionaire's tax, and the pending sales tax on interstate Internet purchases known as...