Ross Garber is a CNN Legal Analyst. He teaches about political investigations and impeachment law at Tulane Law School and has served as lead counsel for four U.S. governors in impeachment proceedings. The opinions expressed in this commentary are his own. View more opinion at CNN.

(CNN) Last week the White House threw down the gauntlet in the face of a demand for information from House Oversight and Reform Committee Chairman Elijah Cummings (D-MD).

Ross Garber

The committee is seeking documents and other materials related to White House security clearance procedures, an issue that has gotten more scrutiny amid reports that the President granted his daughter Ivanka and son-in-law Jared Kushner top level security clearances over the objection of his chief of staff and White House counsel.

Instead of providing information, the White House sent Cummings a letter in which it explained why the House isn't entitled to what it is seeking. This battle of wills could result in significant, long-term consequences for future Congressional efforts to get information from presidents.

It's important to note that Cummings made his information demand in a letter, not a subpoena. This reflects both a respect for the institution of the presidency and the practical reality that courts will consider enforcing Congressional subpoenas against the executive branch only once Congress has shown that it has exhausted all reasonable efforts to negotiate a resolution. In other words, Cummings is hoping to get as much voluntary compliance as he can from the White House and lay the groundwork for potential litigation should that fail.

In the face of this informal demand, the White House responded as expected. It said it is willing to offer reasonable accommodations to the Committee's demands -- signaling to the courts that no judicial intervention is yet warranted if Congress tries to enforce a subpoena -- while also forcefully asserting two substantive reasons for not providing information.

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