Dr David Graham, the US Food and Drug Administration (FDA) official who caused a stir in 2004 by criticising the agency’s handling of Merck & Co’s withdrawn painkiller Vioxx, will be called to testify in court cases alleging injury by the drug.

The judge handling an ongoing Vioxx court case refused to grant a motion by the US government, which asked for an attempt by lawyers representing the plaintiffs to force Graham to give evidence in the case to be denied.

Graham told a Senate hearing into the withdrawal of Merck's painkiller Vioxx in 2004 that the FDA was "incapable of protecting America against another Vioxx,” and has accused the agency of intimidation that forced him to withdraw a presentation due to be presented at an FDA advisory committee meeting as recently as last February.

Getting Graham to testify at the trial is a real boost to the plaintiffs, as he could undermine one of Merck’s defense arguments - that Vioxx was safe because the agency approved the drug, according an Associated Press report.

Merck pulled Vioxx off the market in September 2004 after a study showed the COX-2 inhibitor doubled the risk of heart attacks and strokes when taken for 18 months or more. The company is still facing thousands of lawsuits brought by patients who claim Vioxx caused them harm, but so far has won three of the four cases that have come to trial, and lost another in which the plaintiff was awarded damages of $253 million (cut to $26 million under state capping laws).