The U.S. Treasury Department has incorrectly labeled China a manipulator of its currency. An important distinction exists between devaluing a currency and currency depreciation. Devaluing implies the People’s Bank of China actively manipulated the value of the Chinese renminbi to gain unfair advantage for its exports. Depreciation simply means the renminbi has lost purchasing power relative to the U.S. dollar, based on market forces. There’s no indication that China is actively devaluing its currency. However, according to the Treasury Department, China met a broad definition of manipulation laid out in the Omnibus Trade and Competitiveness Act of 1988, which says...