Former Rep. Wayne Gilchrest was a Republican member of Congress who represented Maryland's 1st District from 1991-2009. Former Rep. Nick Rahall was a Democratic member of Congress who represented West Virginia's 4th and 3rd districts from 1977-2015. The views expressed in this commentary belong to the authors. View more opinion articles at CNN.

(CNN) For members of Congress, there are some principles that should take precedence over others. The first of those is to uphold and defend the Constitution, which includes the systems of separation of powers and checks and balances. Another is to preserve the integrity of the institution of Congress as a coequal branch of government by conducting legitimate oversight and holding the other branches accountable. Sometimes, members have to make the choice to prioritize these fundamentals of our democracy over party loyalty. We know firsthand that it can be hard to do, but we urge today's members to rise to the occasion.

Wayne Gilchrest

Overseeing the executive branch is often a contentious process, but there are rules in place to make sure that the process works. In fact, congressional authority to conduct oversight is rooted in its most fundamental constitutional power: legislating. In order to assess existing laws or consider new ones, Congress has to be able to uncover, and even compel, information. As the Supreme Court has noted , Congress's power clearly extends to oversight of executive agencies, which Congress created and funds. Congress can get the information it needs in many ways, whether by holding hearings or requesting documents. When asking doesn't work, Congress can compel responses through subpoenas and punish people by holding them in contempt.

Though it is unfortunately and dishearteningly normal for presidents to resist congressional oversight to a certain extent, the Trump administration may be taking such resistance to a new level. Attorney General William Barr recently refused to appear before the House Judiciary Committee while simultaneously refusing to comply with a subpoena from the committee requesting access to the unredacted Mueller report and supporting documents. The Trump administration has also refused to provide the House Ways and Means Committee with the President's tax documents that it has requested.

Recent comments by President Trump and other administration officials indicate that they may go so far as to categorically defy all oversight subpoenas. And indeed, individuals tied to the Trump administration are actively defying multiple subpoenas . Meanwhile, Trump has sued multiple banks to block the House Intelligence and Financial Services committees from gaining access to his financial records, which they had requested.

Nick Rahall

Reasonable people can disagree on the merits of particular investigations, but what we should all be able to agree on is the constitutionally embedded reality that Congress has both the right and the duty to conduct oversight of the executive branch, and that congressional subpoenas in particular must be honored -- no matter the context. If these subpoenas are ignored, it is incumbent upon all members of Congress, regardless of party, to consider citations of contempt against the relevant administration officials.