A reporter friend once asked, rhetorically, "What member of Congress would you least want to make enemies with?"

"I don't know," I said. "Harry Reid? Nancy Pelosi?"

"Wrong," he replied. "Henry Waxman."

And he was right. Waxman is Congress's most aggressive investigator, and drawing his critical eye will land you in front of his committee, answering some tough, direct questions. He will demand answers, and hundreds of pages of documents.

Waxman relentlessly dogged industries and government agencies through his oversight authority in several committee positions. In the 1980s and 1990s, Waxman dragged tobacco executives before Congress to answer for the health effects of cigarettes. He brought Major League Baseball players to the Capitol to answer for steroid use. During a two-year window from 2007 to 2009, when Democrats ran Congress and President Bush still ran the White House, Waxman made it his mission to hound the Bush administration for potential misdeeds, actually adding the word "Oversight" to the committee's official name when he took control of it. He subpoenaed Condoleezza Rice on the intelligence used to justify the invasion of Iraq; he subpoenaed the Department of Justice repeatedly for e-mails related to the Valerie Plame Wilson leak; he subpoenaed for FBI transcripts of interviews with Bush and Vice President Dick Cheney about Plame.

The administration cited exemptions under "executive privilege" for many of his requests. Waxman banged his gavel and pressed on.

For the past year and a half, Waxman has been preoccupied. At the outset of Barack Obama's presidency, he left the Oversight and Government Reform Committee to become chairman of Energy and Commerce, with the intent of working on energy and health care. And that's exactly what he's done. Waxman drafted and helped pass (by one vote) the House's Waxman-Markey cap-and-trade energy reform legislation. His committee wrote a large portion of the House's health care reform bill. Waxman examined Toyota's faulty brakes and pushed related legislation, but he's largely been deprived of the time and opportunity to sink his teeth into big investigations.

BP's massive oil spill in the Gulf of Mexico has changed all that.

The disaster falls under Waxman's committee jurisdiction at Energy and Commerce, and he has launched an investigation, along with Oversight and Investigations Subcommittee Chairman Bart Stupak, into how the spill happened and the corporate and governmental response to it.

The top executives of companies involved in the Deepwater Horizon well--Transocean President and CEO Steven Newman, BP American Chairman and President Lamar McKay, and Halliburton Global Business Lines President Tim Probert--all appeared before a subcommittee hearing on the spill earlier this month. The subcommittee has received hundreds of thousands of pages of documents, as well as testimony of EPA Administrator Lisa Jackson, former Minerals Management Service head Elizabeth Birnbaum, academics, and other administration officials regarding the spill and response.

"It is now five weeks since the Deepwater Horizon disaster and each day brings more discouraging news of the devastation this oil spill is causing to the economy, to the environment, and to the people of the Gulf coast region," Waxman said to open the last hearing, held on Thursday, at which he suggested BP's internal investigation of the spill has been incomplete.

"Each day, we are learning more about the cascade of mistakes and misjudgments that caused this catastrophe," Waxman said.

So far, oil executives have been forthcoming with documents and information, according to a congressional aide, and on Thursday, Waxman and Stupak asked for more, reuqesting all documents related to several technical drilling decisions BP made at the Deepwater Horizon well.

The Obama administration won't evade Waxman's scrutiny, either: the two congressmen will likely request documents from the administration too, according to the aide.

Will the oil spill become Waxman's next investigative crusade? With health care passed and energy stalled in the Senate, his plate has been cleared of major portions of the Democratic legislative agenda. It only seems fitting that he would delve into the Deepwater Horizon spill.

So far, the subcommittee has been asking questions but hasn't produced recommendations or legislation. It is gathering information, mostly from BP, and refining its technical questions about the well.

The Energy and Commerce Committee has devoted a section of its website to host information about hearings and .pdf documents of testimony related to the Deepwater investigation. It's also providing the live video feed from the ocean floor.

Waxman and Stupak will hold a field hearing on the morning of Monday, June 7 in Chalmette, Louisiana, as oil washes ashore, polluting U.S. wetlands, and as a dismayed public asks how it is that oil still gushes unabated into the Gulf, and how the severity of the spill went unknown for so long. The administration has thrown blame and pressure at BP, and the press corps has asked he administration why it didn't do more sooner. The New York Times reported that the administration missed chances to act sooner on the spill. Questions have arisen over just how much oil is spilling, and how accurate BP's monitoring has been. 

There is a high demand for a full accounting of just how this happened, who is to blame, and whether BP and the Obama administration responded with appropriate urgency. People want answers. As it just so happens, Congress's most relentless investigator is looking for them.

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