Half of the manslaughter charges against two former BP plc supervisors related to the deaths of 11 men on the Deepwater Horizon rig when the Macondo well blew in April 2010 were dismissed Tuesday.

U.S. District Judge Stanwood Duval of the Eastern District of Louisiana in New Orleans dismissed 11 counts of seaman's manslaughter facing Robert Kaluza and Donald Vidrine, who were the rig well site leaders (U.S. v. Kaluza, No. 12-cr-00265). However, 11 other counts of involuntary manslaughter were not dismissed. A federal Clean Water Act violation also was not dismissed; a trial is scheduled to begin in June.

The original indictment was issued late last year by the U.S. Department of Justice's (DOJ) Deepwater Horizon Task Force (see Daily GPI, Nov. 16, 2012). On the day the indictment was issued, BP agreed to pay $4 billion in penalties and plead guilty to 14 criminal counts.

Kaluza and Vidrine were the highest-ranking BP supervisors aboard the doomed drilling rig, which was owned by Transocean Ltd.

Duval rejected arguments by the defense legal teams that claimed the U.S. Outer Continental Shelf (OCS) Lands Act did not extend federal law to the Deepwater Horizon location. However, the judge accepted the defendants' arguments that the seaman's manslaughter charges did not extend to them as well site leaders because they had no navigation function aboard the platform.

The ruling is the first in the OCS Lands Act's history to to apply to a drilling rig blowout, Duval said. The "risk of explosion onboard deepwater drilling facilities is a grave matter," but he said he would refuse "to expand the scope of the statute unnecessarily without certainty as to Congress' intent to do so."

DOJ officials had no comment on Duval's ruling.

A trial now is under way in New Orleans of former BP engineer Kurt Mix, who is charged with two criminal counts of obstructing justice, after being accused of deleting records related to the amount of oil flowing from the Macondo well after the blowout (see Daily GPI, April 26, 2012). If convicted, Mix faces up to 20 years in prison and could be fined up to $250,000 on each count.