A provision in the federal tax code gives the chairs of the congressional panels with jurisdiction on tax policy the ability to request tax returns from the Treasury Department. That means the Democratic chairman of the House Ways and Means Committee will have the authority in January to demand Trump’s tax returns. George Yin, a UVA law professor, said that in the past when there have been conflicts involving someone resisting requests for information from Congress, courts have ruled that there needs to be a legitimate legislative purpose for Congress’s request.