A judge held a secret hearing Tuesday in the prosecution of a former CIA operative accused of leaking government secrets about Iran to a New York Times reporter, a case where prosecutors are asking for permission to present secret evidence to a jury and also want to keep other government secrets out of public view.

Secrecy is the watchword in the case against Jeffrey Sterling of O'Fallon, Mo., who prosecutors say was a key source of classified leaks for reporter James Risen's 2006 book State of War. The book includes a chapter that details an apparently botched CIA effort to sabotage Iran's nuclear program by supplying flawed blueprints through a Russian intermediary.

Sterling served on the Iranian desk at the CIA and handled Iranian spies who had defected to the United States.

U.S. District Judge Leonie Brinkema closed Tuesday's pretrial hearing to the public, even though several of the motions that were scheduled to be discussed had been debated openly in court papers. As a result, even Sterling's wife was barred from the courtroom.

Some level of secrecy is normal and even expected in cases where classified information could be disclosed. A federal law, the Classified Information Procedures Act, governs the process for deciding how to balance a defendant's right to see the evidence against him and the government's right to protect its secrets.

But in the Sterling case, defense lawyers argue that prosecutors' demands for secrecy and restrictions on the disclosure of classified information go far beyond established precedent and would prejudice Sterling's right to a fair trial. In particular, they object to the "silent witness" rule, which allows jurors to see sensitive information that will never be made public.

Edward MacMahon, Sterling's lawyer, argued in court papers that the awkward logistics of the silent witness rule — which might require closing the courtroom to the public or allowing witnesses to testify behind a screen without revealing their identity — "would unfairly suggest to the jury that the documents are so secret that counsel cannot talk about them, when their alleged status as national security information is one of the very issues of fact the jury needs to decide."

MacMahon also objects to a government request to replace classified evidence it plans to present against Sterling with unclassified substitutions that would purportedly contain the relevant information without disclosing any secrets. MacMahon argues that if the government is truly concerned about protecting its secrets, it should leave any classified evidence out of the case.

Prosecutors, on the other hand, say their requests for secrecy are valid and prevent the defendant from bullying prosecutors into dropping their case for fear of disclosing sensitive information, a practice commonly referred to as "graymail."

Without such secrecy, prosecutors say, they might be forced to disclose the identities of CIA assets as part of a trial.

"To disclose the true identities of certain former and present CIA employees as well as any CIA human assets ... would create real and legitimate national security and personal safety risks," prosecutors wrote in court papers filed last week.

Prosecutors also said they do not know for certain at this point whether they will need to invoke the silent witness rule.

The Obama administration has used espionage statutes to pursue cases against five alleged government leakers, including Sterling, more than any of Obama's recent predecessors.

The government's inability to present its case without disclosing secrets can severely crimp its ability to prosecute those cases. Earlier this year, the government struck a plea bargain with a National Security Agency executive accused of leaking classified information to Baltimore Sun reporter and dropped its most serious charges. The plea deal, which resulted in a sentence of probation, came shortly after a judge refused to allow prosecutors to use unclassified summaries of evidence in place of actual documents that they believed would disclose NSA technology if made public at trial.

Prosecutors in the Sterling case were already dealt a blow earlier in this case when Brinkema effectively quashed a subpoena issued to Risen. Brinkema ruled that Risen can only be compelled to testify about perfunctory matters like confirming he is the author of the book in question. Prosecutors have asked the judge to reconsider her ruling.