It’s not only in sports that “you can’t tell the players without a scorecard.” The huge number of Trump investigations, proposed and actual, would require a spreadsheet. The Justice Department and the New York Attorney General have many entries on that scorecard, but so does Congress. Congress still has several investigations going about Russia, White House security clearances, Trump’s tax returns and, oh wait, there is also Rep. Devin Nunes, R-Calif., investigating Trump investigations.

Although Congress has broad powers of investigation, there is at least one limitation that seems to be ignored: Congress’s power to investigate derives from its power to legislate. Therefore, there should be some connection between what Congress investigates and some kind of legislation, a requirement that in the present environment is little discussed and barely applied.

In fact, one could readily argue that many of the current and potential investigations of President Trump are far more grounded in the politics of attack and very little aimed toward actual legislation.

Although congressional investigations have been around since the country's founding, there is actually no explicit mention of such a power in the Constitution. Instead, Congress and the courts have eagerly implied a power to investigate from Article I, section 8 of the Constitution granting Congress the power to “make all laws.” When the Supreme Court has affirmed the power of congressional investigations, it has frequently underscored the necessary connection to legislation. In Quinn v. U.S. (1955), for example, the court said there was “no doubt as to the power of Congress, by itself or through its committees to investigate matters and conditions relating to contemplated legislation.”

So let’s take the calls by Congress to investigate Trump’s tax forms, for example — and not just returns as president, but for years when he was a private citizen. What legislation is this expected to inform? I suppose Congress could gin up a legislative purpose, arguing that it will consider a bill to require all presidents and presidential candidates to provide these, but that seems a little too cute. In this day and age, Congress cannot even assure that such material would remain confidential, as the law would require. This one certainly seems to travel the low road of politics, not the higher and mandated road of legislation.

Professors Douglas Kriner and Eric Schickler in their 2016 book, Investigating the President: Congressional Checks on Presidential Power, concluded that, especially in the House of Representatives, politics has usually been the common denominator when congressional investigations have grown. Studying 4,522 congressional investigations of the executive from 1898-2014, Kriner and Schickler conclude that a “divided government,” when at least one house of the Congress is controlled by a different party than the White House, “is the single biggest predictor of investigative activity in the House" (p. 67). They add that such investigative activity “significantly erodes the president’s standing with the public” (p. 86), with the media fanning the flames. In this era of partisanship and polarization, “the dangers of overreach have expanded considerably” (p. 249), they say.

I am not arguing that Congress’ power to investigate is not important, or even that it is not broad. In general, I have greater concern about the growing power of the executive branch as compared with the legislative. But, as a 2017 Congressional Research Service report concluded, “Congress’s [investigative] authority is not unlimited.” Congress would not have the power to investigate the private affairs of an ordinary citizen, for example, which Donald Trump was until he ran for and was elected president.

What I am arguing is that in an era when Congress is doing very little legislating at all, we should be wary of allowing its investigative power to become its primary way of doing business. Moreover, we should be doubly wary when the political motives are high and any kind of legislative purpose is low.

David Davenport is a contributor to the Washington Examiner's Beltway Confidential blog. He is a research fellow at the Hoover Institution.