"Either there simply isn't evidence that anybody higher up was involved, or the department has concluded the only way it's going to make its case against more senior corporate officers is if it charges and eventually obtains cooperation from Vidrine and Kaluza," said David Uhlmann, a University of Michigan law professor and former chief of the Justice Department's environmental-crimes section.
Although London-based BP PLC has agreed to plead guilty to charges related to the workers' deaths, none of the company's onshore engineers or executives is accused of wrongdoing in the indictment unsealed Thursday.
Former BP executive David Rainey was charged separately with withholding information about the spill from Congress, but the allegations against him aren't related to the causes of the blowout.
Shaun Clarke, one of Kaluza's attorneys, said the narrow focus of his client's indictment doesn't jibe with the widely accepted conclusion that "multiple failures at multiple levels in multiple companies" led to the blowout.
"It would have taken a lot of courage after spending three years and tens of millions of dollars investigating to go back to the White House and say, 'You know, Mr. President, we can't really find a person to blame.' Instead, they decided to scapegoat two people who were just out on the rig doing their jobs," Clarke said.
Natural Resources Defense Council president Frances Beinecke, who served on a presidential commission charged with investigating the explosion and spill, said the disaster resulted from "systemic failures" that raised concerns about the drilling industry's safety culture.
That commission concluded the blowout was the product of "several individual missteps and oversights" by BP, rig owner Transocean Ltd. and cement contractor Halliburton, with mistakes made both on the rig and onshore. The panel also found that government regulators lacked the authority, resources and technical expertise to prevent the mistakes from occurring.
"Though it is tempting to single out one crucial misstep or point the finger at one bad actor as the cause of the Deepwater Horizon explosion, any such explanation provides a dangerously incomplete picture of what happened encouraging the very kind of complacency that led to the accident in the first place," the commission's January 2011 report says.
Vidrine, 65, was on duty at the time of the April 20, 2010, explosion. Kaluza, 62, had been on the rig only a few days before the blowout. He was in bed at the time of the blast.