With a president as suspect as Donald Trump and legislators as eager as House Democrats, investigations into Trump’s many scandals are not only expected but required.

Yet, to be effective, those probes need quality. Willy-nilly, feel-good efforts might get lots of publicity, which can serve partisan ends, but not result in the impact taxpayers deserve.

A new paper from Paul C. Light, a Brookings Institution senior fellow in governance and a New York University public service professor, provides congressional investigators a framework for their work.

The title, “How the House should investigate the Trump administration,” grabs attention but is a bit misleading. This is not a partisan document aimed specifically at a deceitful man. The better heading is the subtitle: “Lessons from the most important House probes since WWII.”

Those lessons apply to congressional investigations generally, not just for this administration. But now, Trump, who entered office with scandals clanging like tin cans behind a wedding car, has presented the House, newly controlled by Democrats, a target-rich environment.

“Democrats do not want for investigatory targets and platforms,” Light writes, citing the 100 committees and subcommittees they control and the promise of a “subpoena cannon” to probe a reluctant administration.

One reason there are so many targets is that Republicans, who controlled all of Congress during Trump’s first two years in office, largely ignored his outrages.

“We had an investigatory drought,” Light said during a briefing on his report sponsored by the good-government Project on Government Oversight (POGO).

But as the House investigative machinery gets in gear, Light predicts that “many of these investigations are unlikely to produce significant effects.” He previously studied 100 House, Senate and blue-ribbon investigations between 1945 and 2012 and found that just five of 31 in the House had a very significant impact, five had a moderate impact, and 21 had little or no impact.

“Impact is the product of the investigation done well. Bright lights, perp walks, and brutal questioning are no substitutes for thoroughness, determination, persistence, and a commitment to careful fact finding,” his report said, adding that “the quality of investigations … flows from the faithful pursuit of truth regardless of the party in charge.”

So how can legislators increase the odds of conducting quality investigations with impact? Light offers a road map with 10 signposts, including these:

Length: “The House is currently preparing for a fast start in 2019 — speed is of the essence for establishing the chamber’s reputation as an investigatory juggernaut, but the press for immediate conclusions may lead to narrower probes and less depth.”

Bipartisanship: Needs no explanation, but don’t expect any.

Breadth: “Likely to be an early victim of the Democratic demand for results.”

Thoroughness: “The good investigation establishes cause and effect after a deep analysis of the evidence. … Speed is likely to take its toll on investigatory thoroughness.”

Freedom to investigate: “The good investigation is free to investigate every lead and examine any angle without interference from its sponsors, stakeholders, and party leaders.”

Visibility: “The major challenge facing House Democrats in coming weeks is not too little visibility, but too much as committees and subcommittees compete for attention in a turbulent environment. Absent careful priority setting from the Democratic leadership, the packed investigatory agenda may create more heat than light.”

Durability: “The good investigation produces a set of facts and recommendations that exert influence into the future while establishing benchmarks for future oversight.”

One problem with investigating Trump is that there is so much to investigate. In a way, the overload works to his advantage because he has “managed to get by one scandal by having another scandal and then another scandal and another scandal and then it just doesn’t get covered … and people tune out,” said Norman Ornstein, an American Enterprise Institute political analyst and a POGO board member. “And now, I don’t think we could count, during the time we have this morning, the number of scandals.”

Ornstein lamented the lack of an effective probe, despite some hearings, into Trump’s disgraceful child separation program on the southern border, including the checks on journalists seeking to report on related issues.

This is police-state kinds of stuff,” he complained, adding that Congress has not yet had “a model investigation” into it. “The bandwidth is such that for each of these committees, there are so many things to do, and it becomes a question of whether they have the resources to do it,” he said.

House Republicans routinely abdicated their investigatory oversight role regarding the Trump administration. Democrats remember that their House colleagues, along with Senate Majority Leader Mitch McConnell (R-Ky.), set a perverted goal when President Barack Obama was their target. In 2010, McConnell said, “The single most important thing we want to achieve is for President Obama to be a one-term president.”

Although Light told me that “there is always a temptation to use investigations to undermine a sitting president of the other party,” he warns Democrats not to follow the lead set by then-House Speaker John A. Boehner (R-Ohio), whose tenure now seems quaint by Trump-era standards.

Boehner “extolled the constitutional value of oversight but saw investigations as a way to dismantle government, not improve it,” Light recalled. “Having promised to do ‘everything — and I mean everything’ — to stop the Obama administration, Boehner weaponized the investigatory process for maximum political damage.” Boehner did not answer a request for comment.

Light tells House Democrats that they “would do well to remember that Obama won reelection despite McConnell’s promise even as they remind themselves of their longstanding commitment to good-government statutes.”

Good advice, but payback can be sweet.

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