The US Department of Justice has launched civil and criminal investigations into the events surrounding the BP oil spill. Does that mean people who helped cause the spill will be going to jail?

Yes, they might be. Violations of some of the applicable environmental laws, such as the Clean Water Act, can result in severe repercussions.

“Clearly, that’s on the table,” says William Snape, a professor at the American University school of law. “I’d say the odds are greater than 50-50 that someone will get jail time or a probationary sentence.”

In one sense, Tuesday’s announcement of the Justice Department probe into the Deepwater Horizon disaster was a chronicle of a prosecution foretold. Given that 11 people died in the explosion and fire that destroyed the Deepwater rig, and that the oil spill may be the worst environmental disaster in American history, federal law enforcement officials are virtually duty-bound to launch an investigation into what transpired in the Gulf of Mexico on that fateful April evening.

However, the manner in which the White House chose to make Tuesday’s announcement – a televised public statement by Attorney General Eric Holder following a meeting with state attorneys general and federal prosecutors – was something of a surprise. After all, it’s BP that’s in charge of stopping up the well that’s currently pouring oil into the open ocean. In that sense, the administration remains in a working relationship – albeit an uneasy one – with the very firm it’s threatening to prosecute.

The laws at issue here include, among others, the Clean Water Act, which mandates both civil and criminal penalties for violations; the Oil Pollution Act of 1990; and the Endangered Species Act, which penalizes those who injure or kill covered wildlife.

In terms of civil violations all these statutes have fairly strict liability standards. For the Endangered Species Act, prosecutors must prove only that a particular action sickened or killed one endangered sea turtle, say.

Given that low bar, a successful civil prosecution in this case is almost inevitable.

“It’s almost certain that [BP, Transocean, or other firms involved] will be found guilty of something,” says professor Snape, an expert in environmental law.

According to Snape, the more interesting question is whether Interior Department officials will also be prosecuted and found guilty of contributing to the BP disaster.

A number of internal reports have found egregious personal behavior and a too-cozy relationship with industry within the Interior Department’s Minerals Management Service (MMS). If federal officials aided and abetted illegal acts on the part of BP, the Justice Department could pursue them, too.

“There are definitely some government officials who are sweating a little bit right now,” says Snape.

While prosecutors will be considering violations of a number of environmental statutes, the most important one in this case is the Clean Water Act, says James Tripp, a senior counsel at the Environmental Defense Fund. It is a comprehensive law that sets both civil and criminal penalties for a wide range of acts resulting in water pollution.

To meet the standards of a civil prosecution, the government must show that a certain act occurred. To meet the standards of a criminal prosecution, the government must show that someone knowingly and intentionally undertook an active malfeasance.

“That’s altogether different from a civil prosecution, and very serious,” says Mr. Tripp.

But the consequences of the BP oil spill are themselves already serious, and getting worse.

“This is a mind-blowing disaster of international magnitude,” says Tripp. “Certainly the Department of Justice actions [in beginning investigations] are well-founded.

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