In April 2010, the Deepwater Horizon oil rig exploded and began spewing oil into the US Gulf Coast. In all, this released some 134 million gallons of crude over a span of almost three months. Eleven workers were killed in the nation's worst offshore oil spill.

Today, federal prosecutors moved—and a judge agreed—to drop manslaughter charges against two supervisors aboard the Deepwater Horizon when it exploded. This development, in which prosecutors said they believed they no longer could meet the legal threshold for a conviction, means that nobody will go to prison for the disaster that soiled coastlines from Texas to Florida, killed nearly a dozen people, and was an environmental disaster that perhaps brings with it never-before-seen longterm consequences.

The government announced the legal move Wednesday in a New Orleans courtroom. Rig supervisor Donald Vidrine instead pleaded guilty to violating the Clean Water Act, a misdemeanor that likely will result in 10 months of probation and 100 hours of community service. Robert Kaluza, the other supervisor who also was being charged with 11 manslaughter counts, is going to fight a single misdemeanor charge that he also violated the Clean Water Act.

The government's decision was a complete reversal from three years ago when then-Attorney General Eric Holder personally announced the manslaughter charges in New Orleans. While BP as a company has agreed to pay billions in record-high legal settlements, the latest move follows a string of other setbacks in which the government sought to hold individuals accountable.

The father of Gordon Jones, a rig worker who died in the explosion, was unhappy with the government's decision.

"As a result of this court proceeding today, no man will ever spend a moment behind bars for killing 11 men for reasons based entirely on greed," Keith Jones told reporters after Wednesday's hearing.

The Justice Department said in a statement that it dropped the felony charges against the two "because circumstances surrounding the case have changed since it was originally charged, and after a careful review the department determined it can no longer meet the legal standard for instituting the involuntary manslaughter charges."

Other government setbacks in its case against BP include:

David Rainey, a former BP executive, was acquitted this summer of manipulating calculations over how much oil was being released during the 3-month-long spill, and a federal judge dismissed charges that he hindered a congressional investigation.

Kurt Mix, a former BP engineer, won a new trial in July after he was convicted of obstruction charges in connection to allegations that he deleted text messages detailing how much oil was spilling into the Gulf of Mexico. He was sentenced to six months probation after he pleaded guilty last month to a lesser charge.