House Ways and Means Committee Chairman Rep. Richard Neal, D-Mass., is seeking six years of President Trump’s business and personal returns under an obscure 1920s law that grants him authority to request it. Trump’s attorneys have challenged the subpoena.

President Trump’s break with the decadeslong precedent of presidential candidates releasing their tax returns has fueled speculation that he may face conflicts of interest in his business dealings. Tax returns alone are unlikely to show evidence of exposure to foreign influence — one of the issues congressional Democrats say they want to investigate — but could provide investigators with a baseline record to compare to any other financial information they discover.