Robert Lighthizer, appearing today at a hearing focused on his qualifications to lead the Office of the U.S. Trade Representative (USTR). The Senate Finance Committee will evaluate his ability to fulfill USTR’s mission, which emphasizes working “toward opening markets throughout the world to create new opportunities and higher living standards for families, farmers, manufacturers, workers, consumers, and businesses.”
Many nations have trade-distorting policies. Eliminating distortions would benefit U.S. exporters, not to mention people in those countries. The USTR rightly should strive to achieve reforms overseas. However, the USTR should never lose sight of a basic economic reality:

the most important market “throughout the world” that must remain open is that of the United States itself. If our country acts to restrict imports, American living standards will fall rather than rise. There has been much talk lately of imposing new tariffs on imports into this country. Economists across the political spectrum agree that a country always reduces its own economic welfare when it curtails imports
A simple illustration helps to explain this concept. Consider the effect on U.S. consumers of a hypothetical increase in the import tariff on orange juice. The United States currently imports almost half of the 613,000 metric tons of orange juice it consumes. Raising the tariff would have the effect of increasing prices on all domestic consumption, but U.S. orange growers only would benefit from the higher price on the 355,000 tons of orange juice they actually produce. The increase in consumer costs would far exceed the increase in producer revenues. Economic welfare — defined as the overall level of prosperity and living standards — would decline.