A Bloomberg News report that the U.S. Justice Department is considering manslaughter charges in its investigation of BP's oil spill in the Gulf of Mexico played prominently enough Tuesday to drive BP's share price down.

But if criminal charges are filed against individuals involved in the disaster, it would be a rare event. An analysis of industrial disasters by University of Maryland law professor Jane Barrett shows that company managers are almost never charged in industrial accidents -- even in disasters that have killed more people than the 11 men who died in last year's explosion on the Deepwater Horizon rig.

"If they are large corporate entities, what has happened historically is the company pleads guilty, pays a fine and no individuals are prosecuted," Barrett said in an interview with AOL News. "The bigger the company, the less likely there will be individuals held accountable."

The 2005 explosion at BP's Texas City refinery, for example, killed 15 and injured more than 170. BP pleaded guilty and paid more than $130 million in criminal, civil and administrative fines. No one was charged with any offense.

"How the Justice Department handles this case is going to be important," Barrett said. "If they are able to prosecute individuals, they'll send a message that a large corporate criminal find won't shield culpable individuals from prosecution."

Yet Barrett, who spent two decades prosecuting environmental cases for the Justice Department and the state of Maryland, and others concede that criminal charges are tough cases to make.

"In a lot of situations, it's hard to find somebody above the level of line employees who has that knowledge that would make them liable," said Steve Solow, a former federal prosecutor who headed the Justice Department's environmental crimes unit. "Is it right to go after someone just doing their job as well as they could, when the issue is far more complex and broader than what their job presented?"

Last June, U.S. Attorney General Eric Holder stood before the microphones in New Orleans to announce the launch of the Justice Department's investigation into the April 20 explosion at BP's well.

Teams of investigators from the Justice Department, Environmental Protection Agency and FBI set up shop in an office building across the street from the federal courthouse in New Orleans. Prosecutors from the Justice Department's criminal division and its environment and natural resources division worked with prosecutors in the New Orleans U.S. attorney's office on several simultaneous, separate and overlapping probes into the fire on the rig, the explosion that set it off and the aftermath.

Earlier this month, the separate inquiries were consolidated into a single special task force in the department's criminal division, headed by John Buretta, a senior prosecutor best known for his prosecutions of mob figures.

The shift signaled not so much a change in scope as a re-concentration of manpower.

"It's not a matter of perspective. It could be a significant matter of resources," Solow said. "In the environmental crimes unit, we hired more people with criminal prosecution backgrounds than environmental backgrounds. These are criminal cases."

The lapse of time also suggests that prosecutors may be trying to construct a more complicated criminal case instead of settling for a large fine.

"They could bring criminal charges against the company for violations of the Migratory Bird Act and the Clean Water Act," Barrett said. "These are easy cases they could bring, given what happened.

"The challenge is in figuring out if there is some criminal conduct that you can pin on an individual," she continued. "Did a senior VP of BP tell them, 'I don't care what you do, this rig has got to be done by this date'? Did they know materials they were dumping to disperse the oil were more toxic than they let everybody else know? Somebody made those decisions. That's what the Justice Department is going to have to figure out."

Laura Sweeney, a Justice Department spokeswoman, confirmed the details about the task force, but declined comment on the investigation itself. A spokesman at BP declined to respond to an inquiry for comment.

What may be more relevant to the investigation, beyond whether prosecutors are able to build a criminal case against individuals, is how prosecutors consider the prior history of the companies involved in the Gulf disaster.

"If you look in the Justice Department guidelines for federal prosecution of organizations, you'll see a specific provision: Is there a past history of violations and what is it?" Solow said. "You look at their past record, and that will be a guide to how seriously you might enforce the current alleged violations."

Barrett said she cataloged 10 years of environmental and worker safety charges for which BP has pleaded or been found guilty. She said she has included them in her paper, "When Business Conduct Turns Violent: Bringing BP ... and Other Scofflaws to Justice," to be published this spring in the Georgetown University Law School's American Criminal Law Journal.

In addition to the 2005 Texas City refinery disaster, BP's previous accidents include:
  • a 2001 explosion at the BP AMOCO plant in Augusta, Ga., that killed three people.
  • a 2006 pipeline rupture in Prudhoe Bay, Alaska, which spilled 6,400 barrels of oil. In 2007, BP pleaded guilty to a criminal misdemeanor and paid a $12 million fine on top of $4 million in restitution payments.
  • another explosion at the Texas City refinery, which killed one person in 2008.
Last fall, BP paid an additional $50 million in fines to the Occupational Safety and Health Administration for failing to correct safety hazards at the Texas City plant that were uncovered during the 2005 investigation. The fine was OSHA's highest ever assessed, and BP was cited for 439 "willful" violations for failures to comply with industry-accepted controls and other violations.

Barrett said she examined industrial accidents dating back to the Exxon Valdez oil spill in 1989. She found little evidence that the system of corporate fines changes corporate behavior.

"To me, this is a prime example of what is wrong with just letting companies buy their way out by paying fines," she said. "The way you change corporate behavior is if you make people within the entity afraid that if they break the law, they can go to jail."