If confirmed, Steven Mnuchin, the nominee to be Donald Trump’s Treasury Secretary, will have a portfolio that touches on many critical issues, including tax policy, financial regulation, international trade, and the myriad conflicts posed by the next President’s opaque business dealings. Also on the list is the matter of whether extremely wealthy investors will have the ability to avail themselves of offshore tax shelters in the future. That last responsibility became a central line of questioning at Mnuchin’s confirmation hearing on Thursday after it was revealed, on the eve of his appearance, that Mnuchin, a hedge-fund manager, had failed to disclose to Congress his role as a director of an investment fund in an offshore tax haven. After a friendly introduction from Senator Orrin Hatch, of Utah, Senator Ron Wyden, of Oregon, the highest-ranking Democrat on the Finance Committee, began to speak. He started by criticizing the “truly disgusting inequity and abuse of America’s tax laws” in general, before turning to Mnuchin’s situation in particular.