Nigeria has filed charges against the pharmaceutical company Pfizer, accusing it of carrying out improper trials for an anti-meningitis drug in 1996.
Pfizer says Nigeria's government was aware of the trial
What is the case about?
In 1996, thousands of people were dying from an outbreak of meningitis across northern Nigeria. Thousands more were paralysed by the disease.
Families were urged to take their sick children to Kano's infectious diseases hospital to receive treatment.
This is where Pfizer was testing a new antibiotic, Trovan, which was given to some 200 sick children.
About 50 children, officials say, died and more developed deformities. But Pfizer says only 11 died.
The Nigerian government says these were caused by Trovan and says Pfizer did not get authorisation before giving out the drug. It wants $7bn in compensation.
Pfizer denied this, says the trials were carried out according to local and international law and that Trovan helped save lives during the meningitis outbreak.
Trovan has since been licensed for use by adults in the US but not Nigeria.
Why has it taken so long to go to court?
It is not entirely clear.
It may be no coincidence that this case has been filed just a week after President Olusegun Obasanjo stepped down.
His government was never keen on taking action despite pressure from Kano State government, which first sued Pfizer in 2005.
The 2001 offical report into the deaths was never published and the panel's head, Abdulsalam Nasidi, has claimed he has received death threats.
The first Kano State case did not make any progress and new legal papers were filed in May, with the first hearing on Monday, 4 June, when a lawyer from Nigeria's Attorney General's office also filed papers on behalf of the federal government.
Strangely, this action has been taken even before the new President Umaru Yar'Adua has appointed a new health minister.
What impact has this case had in Nigeria?
The effects are still being felt a decade later.
The problems associated with this trial were one reason why several states in northern Nigeria refused to take part in a mass polio immunisation campaign organised by the World Health Organization some years ago.
Some local Islamic preachers said there was a western plot to sterilise Muslim women.
After several tests were carried out to proving the vaccine's safety, the programme has now been resumed.
But because so many people had not been vaccinated, polio spread from northern Nigeria and also returned to neighbouring countries, where it had been wiped out.
There remains some significant resistance to the polio vaccine in northern Nigeria.