


Still, Mr. Holder's decision to confirm the probes Tuesday, in a staged appearance on the Gulf Coast, appears to be in line with the department's guidelines in high-profile cases. Mr. Holder stressed that 11 people died in the April 20 rig accident that precipitated the spill and said there is "a wide range of possible violations."

Mr. Holder, left, announces that the Justice Department has launched civil and criminal investigations into the oil spill, in New Orleans on Tuesday. Associated Press

Facing growing criticism over its response as the leak drags on, the Obama administration has been pushing aggressively on several fronts to show it is in command of the situation and to keep pressure on BP.

But it faces a tricky balance keeping up that pressure and showing the public it is taking action even as it depends heavily on the company, and its technical expertise, to stop the flow from the crippled well.

Legal Environment

2009: ExxonMobil Corp. pleads guilty to killing migratory birds in five states, pays roughly $7,000 for each bird killed for a total of about $600,000

2007: Citgo Refining and Chemicals Co. goes to trial and is found guilty of three misdemeanor criminal violations of the Migratory Bird Treaty Act by a judge in Corpus Christi, Texas

2007: BP subsidiary agrees to plead guilty to an environmental crime and pay $50 million in connection with a deadly explosion at a refinery in Texas two years earlier.

1989: Exxon Valdez tanker crash and oil spill results in criminal and civil charges, lawsuits costing Exxon more than $4.3 billion, including compensatory and cleanup payments, settlements and fines.

Inside the department, some officials feared that the threat of agents of the Federal Bureau of Investigation looking over the shoulder of BP and others could hinder the work to plug the well, people familiar with the debate said.

Mr. Holder sought to at least tacitly address those concerns Tuesday when he said the government's first priority was to stop the spill.

The department usually doesn't discuss investigations until charges are filed.

But Mr. Holder's defenders pointed to guidelines from the U.S. Attorney's Manual, the Justice Department's bible for handling prosecutions, which allows officials to confirm ongoing probes "in matters that have already received substantial publicity, or about which the community needs to be reassured that the appropriate law enforcement agency is investigating the incident."

Most of these companies were aware that a Justice Department investigation was under way. For weeks, the department has been dropping hints that it was taking preliminary steps toward an investigation.

Mr. Holder told reporters last month that he had dispatched senior prosecutors to the Gulf of Mexico region. More recently, the department sent letters to companies involved in the accident asking them to preserve all relevant documents.

Oil stained the big toe of William Barnett while he collected orange-colored tar balls on a public beach Wednesday in Dauphin Island, Ala. Getty Images

The question is what will come of it—amid some very real hurdles. The very fact that there is oil in the water indicates a violation of federal environmental laws, one Justice Department official argued.

Whether that leads to a criminal case for the companies involved in the Deepwater Horizon operation—BP, rig owner Transocean Ltd. and other contractors—may depend on whether the government concludes that willful violations of the law led to the rig explosion that led to the spill.

The Justice Department's environmental section has been aggressive in pursuing cases against corporations—though many end up with misdemeanor pleas and fines that are easily absorbed by big companies.

BP didn't return requests for comment on its legal strategy for defending itself in a criminal investigation.

Transocean's position is that it was following BP's orders and that the engineering of the well was BP's design and responsibility.

It has hired outside lawyers and is seeking BP's engineering documents to review them for faults.

The company would not comment other than to say through a spokesman: "Transocean has not been named in any criminal investigation. We will not speculate on actions the Justice Department may or may not take."

Mr. Holder on Tuesday said investigators were reviewing environmental laws, such as the Clean Water Act, the Oil Pollution Act, the Migratory Bird Treaty Act and the Endangered Species Act, to see if there were violations.

Some measures, such as the bird act, allow prosecutors to prove a violation without having to show that a company intended any wrongdoing, thereby lowering the bar to fine corporations.

Mr. Holder said officials also were reviewing other statutes.

Legal experts said those likely included fraud and obstruction of justice.

Also, prosecutors will look at whether BP and others made any allegedly false statements to government officials at the Minerals Management Service, the U.S. Coast Guard or the Environmental Protection Agency, either before or after the explosion at the Deepwater Horizon oil rig.

Last year, Exxon Mobil Corp. pleaded guilty to killing migratory birds in five states and paid roughly $7,000 for each bird killed, for a total of about $600,000.

In 2007, Citgo Refining and Chemicals Co. went to trial and was found guilty of three misdemeanor criminal violations of the Migratory Bird Treaty Act by a judge in Corpus Christi, Texas.

It could take months or even years before the Justice Department can build a case that is ready for a courtroom.

BP and its contractors have hired multiple law firms to represent their interests, as have some individual officials at the various companies involved.

They already have pointed fingers at each other in a series of public hearings before members of Congress, and before an investigative panel led by the Coast Guard and the Minerals Management Service.

White-collar criminal defense attorneys said BP and other companies in the government's crosshairs likely will insist the event was an accident.

On Tuesday, the Justice Department asked a Houston court to reject Transocean's effort to limit its liability for the oil spill to around $27 million by invoking a 159-year-old law.

The Limitation of Liability Act of 1851 was previously invoked by the owners of the SS Titanic to avoid liability when the supposedly unsinkable ship sank.

BP has had previous legal clashes with the U.S. government. In 2007, a BP subsidiary agreed to plead guilty to an environmental crime and pay $50 million for violating the Clean Air Act in connection with a deadly explosion at a refinery in Texas two years earlier. It also paid $20 million in connection with an oil spill in Alaska and was charged with a misdemeanor.

Also in 2007, BP paid $303 million in criminal and civil penalties and restitution for driving up the price of propane several years earlier. The agreement included a three-year period of probation and the appointment of an outside monitor to oversee compliance efforts.

—Thomas Catan and Amir Efrati contributed to this article.

Write to Evan Perez at and Dionne Searcey at