Good catches
Here is how McGrain is described
The Court upheld Daugherty’s contempt conviction, establishing a presumption that congressional investigations have a legislative purpose. This presumption was not overcome by showing that the committee also had another purpose, such as exposure of wrongdoing. This presumption would later restrict the Court’s hand in clear cases of congressional overreaching while investigating communists after World War II.
this summary was a little ambiguous, so I read some of the actual case…
and here are a few key quotes from the summary
- Each house of Congress has power, through its own process, to compel a private individual to appear before it or one of its committees and give testimony needed to enable it efficiently to exercise a legislative function belonging to it under the Constitution. P. 273 U. S. 160.
- The two houses of Congress, in their separate relations, have not only such powers as are expressly granted them by the Constitution, but also such auxiliary powers as are necessary and appropriate (Page 273 U. S. 136) to make the express powers effective, but neither is invested with “general” power to inquire into private affairs and compel disclosures. P. 273 U. S. 173.
- A witness may rightfully refuse to answer where the bounds of the power are exceeded or the questions are not pertinent to the matter under inquiry. P. 273 U. S. 176.
- A resolution of the Senate directing a committee to investigate the administration of the Department of Justice – whether its functions were being properly discharged or were being neglected or misdirected, and particularly whether the Attorney General and his assistants were performing or neglecting their duties in respect of the institution and prosecution of proceedings to punish crimes and enforce appropriate remedies against the wrongdoers, specific instances of alleged neglect being recited – concerned a subject on which legislation could be had which would be materially aided by the information which the investigation was calculated to elicit. P. 273 U. S. 176.
- It is to be presumed that the object of the Senate in ordering such an investigation is to aid it in legislating. P. 273 U. S. 178.
- It is not a valid objection to such investigation that it might disclose wrongdoing or crime by a public officer named in the resolution. P. 273 U. S. 179.
- A resolution of the Senate directing attachment of a witness who had disobeyed a committee subpoena to such an investigation, and declaring that his testimony is sought with the purpose of obtaining "information necessary as a basis for such legislative and other action as the Senate may deem necessary and proper," supports the inference, from the earlier resolution, of a legislative object. The suggestion of “other action” does not overcome the other part of the declaration, and thereby invalidate the attachment proceedings.
This, IMHO, is the case that takes Kilbourn v Thompson’s finding of the need for a legislative purpose and turns it into the need for mere a pretext of legislative pupose. The decision makes it clear that there are limits to Congress’s authority (“8…neither is invested with “general” power to inquire into private affairs and compel disclosures”), but authorizes compelled testimony as long as a legislative purpose can be established.
Sinclair v US merely affirms point 9 above --“A witness may rightfully refuse to answer where the bounds of the power are exceeded or the questions are not pertinent to the matter under inquiry” and McGrain v Daugherty is cited as precedent.
It should also be noted that Sinclair relies upon powers conferred to congress in other parts of the constitution (not art 1 sec 1) – specifically Art 4, sec 3… and that might be relevant to the question at issue here.
And THAT being said, I’m don’t see the particular relevance of Sinclair here – its not about compelled testimony by a witness, its about a subpoena to a 3rd party. And while the investigation itself may not have the necessary legislative purpose, the documents are relevant to the investigation. In Sinclair, the witness was asked questions having nothing to do with the subject of the investigation he’d been called to testify on.