Getty Images/Al Riccio

Yesterday, the Obama administration delivered its first rebuff to its most left-wing supporters. In a San Francisco courtroom yesterday, a Justice Department lawyer told judges that the Obama administration would "stand by" a brief filed by the Bush administration.

This short answer might not seem very dramatic. But it contains a lot of meaning.

The brief relates to a case filed on behalf of Binyam Mohammed, an Ethiopian citizen who claims British residency.

Mohammed was born in 1978. In 1994, his father sought asylum in the UK and brought his family with him. The father would later return to Ethiopia, but Mohammed stayed and became increasingly intensely religious. In the summer of 2001, Mohammed left Britain to travel to Afghanistan. Mohammed's supporters explain that the young man wanted to see whether Afghanistan was a "good Muslim country." US and UK intelligence believe he enrolled in a terrorist training camp.

In April 2002, Mohammed was arrested by Pakistani police at Karachi Airport as he sought to fly to Britain on a false passport. He passed through prison facilities before ending up at the prison at Guantanamo Bay in September 2004. US officials believed he had been involved in a plot to build and smuggle a dirty bomb into the United States.

In 2005, Mohammed was charged before a military commission. The prosecution has gone through many stops and starts. At the moment it is stopped, but Mohammed remains at Guantanamo.

Mohammed's supporters have flung some big accusations--and are making big demands. They claim that the US government injected Mohammed with heroin to reactivate an old addiction and render him dependent. They say that he has been tortured. And they want him immediately released to take up residency in Britain, a country of which he is not a citizen.

More recently, they have begun filing lawsuits. They have sued in British court to demand that the British government release information about Mohammed that might corroborate claims of abuse.

And--here's where the Obama part comes in--in San Francisco they sued a Boeing subsidiary, Jeppesen Dataplan, for providing services that enabled the CIA to fly Mohammed to overseas prisons.

That case was dismissed by a lower federal court. The ACLU, acting for Mohammed and four others, appealed. On appeal, the Bush administration argued that the case threatened to reveal essential national secrets. Yesterday, a three-judge panel asked if the new administration wished to withdraw that argument. Answer: No.

Notice something else though. The ACLU is not suing to get Mohammed released. It is filing a civil lawsuit, aimed at extracting money. It's these civil suits that are the next frontier of terrorism litigation. Will the Obama administration hold fast against its trial bar allies? That's the most pressing national security question in this new era.

David Frum is a resident fellow at AEI.