NEW ORLEANS (AP) -- Lawyers for two BP rig supervisors charged with manslaughter in the Deepwater Horizon disaster say the indictment should be dismissed because prosecutors accuse the men of violating standards that didn't exist when an explosion killed 11 workers on April 20, 2010.
Robert Kaluza and Donald Vidrine are scheduled for trial June 2 on 11 counts each of involuntary manslaughter and "seaman's manslaughter."
They have pleaded not guilty to charges that they botched a key safety test and disregarded abnormally high pressure readings that prosecutors described as glaring signs of trouble before the blowout of BP PLC's Macondo well.
Federal rules at the time "did not even mention — much less require" the test in question, according to a 33-page memorandum filed with the motion on Thursday.
"This case involves a highly technical field, in which courts should be particularly suspicious of second-guessing under 'standards' that have been developed after the fact," they wrote.
A Justice Department spokesman did not immediately respond to a request for comment.
U.S. District Judge Stanwood Duval has not ruled on an earlier motion to dismiss the charges. He heard those arguments Sept. 18.
Prosecutors contend that BP should have investigated the pressure readings even though the Transocean drill crew explained them and even though no rules or industry standards required the BP workers to do more than they had been told, the attorneys argued.
Transocean was the rig owner.
"With perfect hindsight, the government has constructed a new standard for this prosecution — one that did not exist on April 20," they wrote.
That makes the law's application in this case unconstitutionally vague, the attorneys said.
"The purported 'standards' on which the government relies — take 'necessary' precautions to control the well, and 'be safe'" are not clear, they wrote.
The explosion that killed the rig workers triggered the nation's worst offshore oil spill. A separate trial, resuming Monday, will look at just how much oil gushed into the Gulf of Mexico in the 86 days before the well was capped and what BP and its contractors did to stop the flow.