The drugmaker says the $2 billion lawsuit should be dismissed because its researchers didn’t do any harm and, in fact, saved lives when they gave children an experimental drug during a 1996 meningitis epidemic, The Washington Post reports.

In a 26-page brief filed in the northern Nigerian state of Kano, Pfizer described the clinical drug trial of its Trovan antibiotic as Trovan as legal and ethical. The filing provides the New York company’s most complete defense since Nigerian authorities levied 31 criminal charges and $8.5 billion in civil claims against Pfizer and its representatives, the paper writes.

Nigerian authorities filed four legal actions in May in state and federal courts. They allege that the Trovan trial led to the deaths of 11 children and injured 189 others. Nigerian prosecutors also say Pfizer didn’t tell families that their children were participating in a drug experiment. Pfizer’s response addresses only allegations made in the civil case in Kano state court, not a separate criminal case.

Pfizer’s lawyers assert in the filing that “all clinical evidence points to the fact that any deaths were the direct result of the meningitis itself…The defendants always acted in the best interest of the children involved, using the best medical knowledge available,” the filing says. “The defendants believed Trovan could save lives.”

Pfizer claims the survival rate was 94.4 percent for children given Trovan and 93.8 for a comparison drug. The survival rate for the rest of the hospital, where the aid organization Doctors Without Borders was treating victims of the epidemic, was about 90 percent.

Pfizer said that local nurses told parents they could choose whether their children would be treated by Pfizer or by Doctors Without Borders, which was administering a proven antibiotic. The company said it explained the trial to parents and obtained their consent orally before it enrolled their children in the study.

But authorities allege Pfizer’s lead researcher concocted and backdated a document that purported to show that a Nigerian ethics committee had approved the trial. Pfizer responded in its filing that such approval was not required under Nigerian law. The company added that it “did not fraudulently procure” the document.

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