But several attorneys for victims of the blast, which killed 15 people and injured more than 170 others, objected to the plea, calling the proposed fine "trivial." They also said the deal doesn't push to improve safety at the plant or fully detail BP's history of safety violations.
The judge agreed to let them voice their complaints and delayed her decision on whether to accept the plea.
Several relatives of workers killed in the accident as well as some injured workers have asked to speak against the plea during Monday's court hearing.
At the hearing, Rosenthal could do one of three things: accept the plea, reject it or order a presentence report, further prolonging the case.
Such reports are standard in criminal cases and offer a judge a wide range of information, such as a defendant's criminal history, that is used in determining a final sentence.
BP and the Department of Justice, who don't want such a report to be done, have defended the plea agreement, saying it's the harshest option available in assessing criminal punishment for the blast.
The fine and plea were part of an October agreement by BP to pay $373 million to settle various criminal and civil charges. In defending the plea agreement, BP has said it has accepted responsibility for what happened, worked hard to improve safety at the plant and has fully cooperated with the criminal investigation.
BP has said it has paid more than $1.6 billion to compensate victims.
The explosion at the plant, about 40 miles southeast of Houston, occurred after a piece of equipment called a blowdown drum overfilled with highly flammable liquid hydrocarbons.
The excess liquid and vapor hydrocarbons then were vented from the drum and ignited as the isomerization unit -- a device that boosts the octane in gasoline -- started up. Alarms and gauges that were supposed to warn of the overfilled equipment did not work properly.
The U.S. Chemical Safety and Hazard Investigation Board, one of several agencies that investigated the accident, found BP fostered bad management at the plant and that cost-cutting moves by BP were factors in the explosion.
