Opinion: The law is clear: Congress should get Trump's tax returns

The power of Congress to investigate and obtain documents to carry out its legislative powers and oversight of the executive branch is well established. The Supreme Court has long recognized that Congress' authority to obtain information necessary to conduct oversight and investigations is necessarily broad. In 1975, Chief Justice Warren Burger, reaffirmed that "'the scope of [Congress's] power of inquiry . . . is as penetrating and far-reaching as the potential power to enact and appropriate under the Constitution'" and that, ancillary to Congress's oversight and investigative authority, the "[i]ssuance of subpoenas . . . has long been held to be a legitimate use by Congress of its power to investigate."