A high-profile defense lawyer in a major CIA bribery case is using a subtle form of extortion that could delay or undermine his client's trial, government prosecutors accused in a new court filing.

Attorney Mark Geragos is refusing to submit to a background investigation required to grant him a security clearance, which would allow him to review classified evidence against his client, Brent Wilkes. 

Geragos has represented such "name" clients as pop legend Michael Jackson, convicted wife-killer Scott Peterson, former Congressman Gary Condit and actress Winona Ryder, among others.

Wilkes, who ran San Diego, Calif.-based intelligence contractor ADCS Inc., is charged with bribing former Congressman Randy "Duke" Cunningham and former CIA executive director Kyle "Dusty" Foggo for government contracts and other favors.

"I think the [government's] constitutional obligations" to turn over relevant documents and information "trump any statutory provision" to protect classified information, Geragos argued in an earlier filing.

In a motion filed late last week, government lawyers accused Geragos of "practicing a...subtle variation of graymail," a tactic used by defense lawyers in national security cases to force the government to drop criminal charges or risk compromising national secrets.

A call to Geragos' Los Angeles office was not immediately returned.

In traditional "graymail," a defendant attempts to derail the government's case against him by demanding classified information be introduced as evidence, to be shown to a jury and placed in the court record.

In a recent example, I. Lewis "Scooter" Libby, former aide to Vice President Dick Cheney, was accused of graymail last year when he attempted to enter a stack of top-secret CIA briefing documents into the court record as part of his defense against charges stemming from the leak of one-time CIA officer Valerie Plame's identity.

In Wilkes' case, Geragos wants the government to choose which secrets are most important for his client's defense and release those -- or face accusations of withholding evidence.

"Such a course of conduct...presents a parade of horribles," including the inadvertent identification of clandestine CIA officers and operations, a years-long delay of Wilkes' trial and the possibility that a conviction could be reversed on appeal, federal prosecutors argued.

Washington, D.C., lawyer Mark Zaid, who has built a career out of representing CIA operatives and other national security figures, sounded puzzled by Geragos' effort.

"You've got to come up with innovative tactics when you're working with the government in these cases," he told ABC News, "but in this case I'm not sure what it's going to gain."

Lawyers for Foggo, whose client was indicted on corruption charges along with Wilkes, have complied with the court's requirements for handling classified information.

In their filing, the government's lawyers told Judge Larry A. Burns they believed he had the authority to disqualify Geragos from representing Wilkes, "the government does not wish to see defense counsel removed from the case."

Instead, they asked Burns to force Geragos to submit to a background investigation; allow federal investigators to probe Geragos' background without his active participation, in order to issue him a clearance; or require Wilkes to hire a second lawyer who was willing to obtain a security clearance.

"What [Geragos] is asking for explicitly would require the court to participate in a crime," Zaid told the Blotter on ABCNews.com.  "The court would be complicit in a crime if they ordered the disclosure of classified information to an unauthorized person."

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