The much-anticipated trial of I. Lewis “Scooter” Libby begins tomorrow in Washington. What follows is a comprehensive spectator’s guide to a legal drama that involves the White House, the CIA, and the press.

Who is the defendant?

I. Lewis Libby Jr., 56, served as Vice President Cheney’s chief of staff and assistant for national security affairs from 2001 until he resigned at the time of his indictment in 2005. Mr. Libby attended Yale University as an undergraduate and got his law degree from Columbia. He served in the State Department and at the Pentagon during the administrations of presidents Reagan and George H.W. Bush. As a private lawyer, he represented a billionaire commodities trader who was a fugitive and was later pardoned by President Clinton, Marc Rich. He was also an early participant in a neoconservative foreign policy group, the Project for the New American Century.

What is the CIA leak investigation?

The probe was launched to determine how the name of a longtime CIA officer, Valerie Plame, appeared in a July 2003 syndicated newspaper column by Robert Novak. Mr. Novak reported that a former diplomat who traveled to Africa at the CIA’s behest to investigate allegations that Iraq sought nuclear materials there, Joseph Wilson IV, was sent on that mission at the suggestion of his wife, Ms. Plame, who worked in the agency’s section assessing the proliferation of weapons of mass destruction. Prosecutors said Ms. Plame’s affiliation with the CIA was classified, though there are disputes about whether she was still considered a “covert” agent at the time of Mr. Novak’s story.

What are the charges?

Mr. Libby faces five federal charges: two counts of making false statements to FBI investigators, two counts of perjury before a grand jury, and one count of obstruction of justice. The indictment alleges that the White House aide deliberately gave the agents and grand jurors false stories about how he learned of Ms. Plame’s CIA affiliation and regarding his conversations with journalists about the issue.

Who was responsible for the leak?

While prosecutors allege that Mr. Libby discussed Ms. Plame with at least three reporters, he does not appear to have been a source for Mr. Novak’s column. The deputy secretary of state, Richard Armitage, has acknowledged that he was the first source for the columnist. Mr. Novak has identified his second source as a top political aide to President Bush, Karl Rove. Some of the disclosures didn’t result in news stories. Before talking with Mr. Novak, Mr. Armitage gave the information about Ms. Plame to a well-known Washington Post reporter, Bob Woodward. Prosecutors allege that Mr. Libby discussed Ms. Plame with a New York Times reporter, Judith Miller, on three occasions. She did not write about the subject until she became caught up in the investigation and served nearly three months in jail for refusing to identify her source.

Is anyone being prosecuted for leaking Ms. Plame’s identity?

No. Mr. Fitzgerald has indicated that a key factor in bringing charges over the leak was whether officials knew that Ms. Plame’s affiliation with the CIA was classified. The statute designed to punish intentional disclosures of the identities of CIA officers and sources is narrowly drawn and requires proof that the defendant knew that the CIA was taking steps to keep secret the officer or source’s identity. It’s not clear whether officials outside the CIA knew of her alleged covert status. Mr. Fitzgerald considered charging Mr. Rove for failing to disclose certain facts to the FBI, but ultimately chose not to charge him, according to lawyers involved in the case. It’s also unclear how much scrutiny the prosecutor gave to Mr. Armitage’s conduct. The former diplomat has said he did not even hire a lawyer to advise him on the matter.

Who is representing Mr. Libby?

Theodore Wells Jr. will lead the defense team at trial. Mr. Wells has had slew of high-profile clients and was recently named lawyer of the year for 2006 by the National Law Journal. Mr. Wells sometimes wins outright victories, such as the acquittal of a former agriculture secretary, Mike Espy, in 1998 on corruption charges brought by an independent counsel. On other occasions, the defense lawyer has managed to prevent convictions of his clients by dividing jurors. In 2003, he won a mistrial for a former investment banker charged with obstruction of justice, Frank Quattrone. The banker was convicted at a second trial but the conviction was overturned. Last year, Mr. Wells won a partial acquittal of a former McKesson Corp. chairman, Charles McCall, on accounting fraud charges.

Mr. Wells, who practices out of the Manhattan office of Paul, Weiss, Rifkind, Wharton and Garrison LLP, is a graduate of Holy Cross College and Harvard Law School. The defense lawyer is a Democrat with close ties to a former senator and presidential candidate from New Jersey, Bill Bradley.

Other members of the defense include a Washington attorney with Baker Botts LLP, William Jeffress Jr.; a San Francisco-based lawyer with Jones Day, John Cline, and an attorney with Philadelphia’s Dechert LLP, Joseph Tate.

Who is the prosecutor?

Patrick Fitzgerald, 46, will argue for the government. He won the conviction of suspects in the 1993 World Trade Center bombing, and of the so-called blind sheikh, Omar Abdel Rahman. Mr. Fitzgerald has been a federal prosecutor for nearly his entire career and was based in Manhattan before moving to Chicago to become the U.S. Attorney for the Northern District of Illinois. He was assigned to the CIA leak investigation in late 2003, after political appointees at the Justice Department in Washington decided the politically sensitive case should be handed over to a special prosecutor.

A Brooklyn native, Mr. Fitzgerald attended Amherst College and Harvard Law School. He has said he has no political party affiliation. His office has pressed corruption investigations against a former Illinois governor who is a Republican, George Ryan, and against aides to Mayor Richard Daley of Chicago, a Democrat.

Mr. Fitzgerald will be assisted at trial by government lawyers from Chicago and Washington, including one, Peter Zeidenberg, who helped lead the prosecution of a top finance official on Senator Clinton’s 2000 campaign, David Rosen. Mr. Rosen was acquitted at trial.

How evenly are the lead lawyers matched?

Mr. Fitzgerald is considered one of the federal government’s best and most tenacious prosecutors, but a former colleague observed that the prosecutor has never faced someone like Mr. Wells, who is one of the lions of the defense bar.

“That’s going to be a huge challenge for Pat, who’s gone up against good lawyers before, but this is a great lawyer,” an attorney who formerly worked with Mr. Fitzgerald, Joshua Berman, said. “This is the all-star game.”

What is likely to be the most compelling moment of the trial?

The testimony of Vice President Cheney, who is expected to be called as a defense witness.

“The highlight for everybody will be seeing Dick Cheney on the witness stand,” a liberal blogger planning to come to Washington for part of the trial, Jane Hamsher, said. “That’s the E-ticket ride.”

“The minute he walks in he’s going to suck the oxygen out of that courtroom,” a law professor at George Washington University, Jonathan Turley, said. “His testimony is very likely to be key. He has the ability to rescue his friend and subordinate.”

Who are the other likely witnesses?

The prosecution is expected to call several prominent journalists, including Timothy Russert of NBC, Judith Miller, formerly of the New York Times, and Matthew Cooper, formerly of Time Magazine. Mr. Libby initially claimed to have learned of Ms. Plame’s CIA affiliation from Mr. Russert. The NBC Washington bureau chief has said he never discussed the matter with Mr. Libby. Ms. Miller and Mr. Cooper are also expected to offer accounts of their conversations with Mr. Libby that are at odds with statements Mr. Libby made about those conversations.

Several former Bush Administration officials are expected to testify for the prosecution, including a former White House press secretary, Ari Fleischer.

The defense has said it will call Mr. Libby to testify on his own behalf. The defense may also try to call Mr. Woodward and other journalists to establish that Ms. Plame identity was being so widely discussed in the summer of 2003 that Mr. Libby may have heard about it from reporters. It’s unclear whether the judge will permit that sort of testimony.

What are the chief arguments of Mr. Libby’s defense?

In court papers, Mr. Libby’s team has suggested two lines of defense. The former White House aide may insist that he accurately described some of the conversations he had with reporters and that the journalists’ recall of those discussions is incorrect. However, Mr. Libby’s main defense is expected to be that he was so busy at the time of those conversations and when he was being questioned by the FBI and grand jury, that he misremembered some of the conversations. “He needs to simply convince this jury that these were busy and heady times and that his memory was not picture perfect,” Mr. Turley said. “I think it’s a winnable case for the defense.”

Mr. Libby’s lawyers could also argue that any misstatements he made were not material to the leak investigation because there was no legal basis to prosecute anyone in connection with leak that started the probe. The defense team has not signaled whether it will raise this in front of the jury, but has jockeyed with prosecutors over jury instructions on this point.

What is the prosecution’s best rebuttal?

Mr. Fitzgerald is expected to argue that the sheer number of contacts Mr. Libby had with White House officials and reporters about Mr. Wilson and Ms. Plame belies any suggestion that Mr. Libby was not focused on the issue.

Does the prosecutor have to prove motive, or why Mr. Libby allegedly lied?

No, and yes. As a technical legal matter, Mr. Fitzgerald only has to prove that Mr. Libby deliberately misled investigators and need not prove why the White House aide did so. However, legal analysts said that, because the defense team is likely to argue that Mr. Libby innocently forgot some details, prosecutors will have to explain why the White House aide may have wanted to cover up his involvement.

“The only place where motive doesn’t matter as something to be proved is in law school and at the court of appeals,” a former prosecutor who once worked alongside Mr. Fitzgerald, Andrew McCarthy, said. “Where the game actually gets played, to convince a jury and prove a case beyond a reasonable doubt, you have to give them a credible narrative.”

Mr. Fitzgerald has agreed not to argue that Mr. Libby committed other crimes, but the prosecutor can still point to the political trouble that could have arisen if investigators found the White House had any role in leaking Ms. Plame’s identity. “It would have been terribly embarrassing,” Mr. McCarthy said.

What about the judge?

Judge Reggie Walton, 57, was appointed to the federal bench by President Bush in 2001. He spent most of the previous 20 years as a superior court judge in Washington. From 1989-2001, he served as the deputy drug czar under President George H.W. Bush.

Judge Walton has a reputation for protecting the right of defendants at trial, but sentencing them harshly if convicted. He is a graduate of West Virginia State College and American University’s law school.

Where will the trial take place?

The trial will take place in Washington at the E. Barrett Prettyman Courthouse, which houses the federal district court and the main federal appeals court in the city. The courthouse has hosted a number of high profile trials including that of John Hinckley Jr. in the assassination attempt on President Reagan and that of the former mayor of Washington, Marion Barry, on drug charges.

How many people will be able to view the proceedings?

The trial will take place on the sixth floor of the courthouse, in Courtroom 16, which can seat about 100 people. Video and audio of the proceedings will be relayed to an adjacent courtroom, which also seats about 100 people, and to a press room on the first floor, which has the capacity for about 50 journalists, according to a court spokesman.

Can the general public attend?

Yes. Several rows of seats in the main courtroom and all of the gallery seating in the overflow courtroom will be available to the general public. During jury selection, the public will probably not be permitted in the main courtroom.

How long will the trial take and when will it be in session?

About 6 weeks, according to various estimates. The trial is to begin each day at 9:30 a.m., with a lunch break from 12:30 p.m. to 1:30 p.m. The trial will not convene on Fridays, when the judge will attend to other cases. This week’s proceedings are expected to be devoted to jury selection and preliminary issues. Opening arguments are set for January 22.

Will the trial be broadcast?

No. In keeping with federal court rules, no press photography or video cameras will be permitted inside the courtroom. A group of press outlets sought permission to broadcast audio recordings of the trial after each trial day concludes, but Judge Walton rejected the request. Video cameras and microphones will be present in the courtroom, though, to provide the closed-circuit broadcast to the overflow courtroom and press room. Television outlets will stake out arrival and departures of the participants from an area in front of the courthouse known as Hinckley Beach, because of the encampment that developed there during the trial of John Hinckley Jr.

Will the attorneys involved recap the courtroom action each day at a news conference?

Highly doubtful. Judge Walton has threatened contempt proceedings against prosecution and defense lawyers who speak publicly about the case. The judge even chastised Mr. Libby’s team for giving reporters a letter from Mr. Fitzgerald to the court correcting an error in one of Mr. Fitzgerald’s public filings.

How much will the trial cost?

The investigation and prosecution cost an estimated $1.44 million through August 2006, according to figures released to the Associated Press under the Freedom of Information Act. A spokesman for Mr. Fitzgerald, Randall Samborn, said about $1.1 million of that amount was an accounting for the work time of personnel already on the government payroll. “We do believe we were very conscientious with the expenditure of taxpayer funds,” Mr. Samborn told the AP. The costs to the court and for Mr. Libby’s defense are not publicly known, though the $3 million raised by his defense fund gives some indication of the legal fees he has racked up.

What is the penalty if Libby is convicted?

In theory, Mr. Libby could be sentenced to up to 30 years in prison and fined up to $1.25 million, if convicted on all five counts. However, judges generally observe federal sentencing guidelines, which would call for a much shorter sentence for a defendant like Mr. Libby, who has no criminal record.

How much has Libby’s legal defense fund committee raised and from whom?

The Libby Legal Defense Trust has taken in more than $3 million from hundreds of donors, according to a person involved with the trust. The trust advisory board is populated primarily by prominent Republicans, including an antidrug activist and former ambassador to Italy, Mel Sembler; a former president of the Public Broadcasting Service, Richard Carlson, and a former Port Authority chairman, Lewis Eisenberg. The panel also includes a former Middle East negotiator under President Clinton, Dennis Ross.

Will Ms. Plame or her husband, Joseph Wilson IV, attend the trial?

Probably not as spectators, though the defense has called Mr. Wilson as a witness. Mr. Wilson has moved to quash the subpoena, but last week Judge Walton rejected that motion as premature.

Why has the case taken so long to start?

When the trial convenes on Tuesday, nearly 15 months will have passed since Mr. Libby’s indictment in October 2005. The delay was due to a variety of factors, including a scheduling conflict on the part of Mr. Libby’s lead counsel and quarreling over the use of classified information in the case. The defense has said it was pleased to have the additional time to prepare.

How many journalists are expected to cover the trial?

About 60 to 70 news organizations have been accredited, according to a court spokesman, including about half a dozen bloggers. Bloggers and other journalists will be permitted to post written material to the Internet from the press room in real time. A blogger for the Huffington Post is also scheduled to fill one of the print pool slots during jury selection.

Could President Bush pardon Mr. Libby, and how likely is that?

The White House has refused to comment on the possibility of a pardon, but Mr. Bush has the authority to pardon Mr. Libby at any time before, during, or after the trial. Mr. Libby has not sought a pardon, probably because he and his allies have described the trial as an opportunity to clear his name. If the former White House aide is convicted, he stands a decent chance of winning a pardon, since people close to the president, including Mrs. Cheney, have described the prosecution as unjust.

What key questions about the case will likely not be answered by the trial?

The trial is unlikely to explore details about how the investigation was launched. Some conservatives have asserted that the report the CIA sent to the Justice Department, triggering the criminal inquiry, must have misstated Ms. Plame’s history at the agency. These critics believe that the CIA’s referral falsely claimed that she had been in covert status overseas in the past five years. Only leaks about agents who have such a record could result in a prosecution under the Intelligence Identities Protection Act.

Mr. Libby’s defense team sought access to the referral, but prosecutors resisted and the judge deemed it irrelevant to the pending charges. The Associated Press and the Wall Street Journal are pressing for a copy of the referral, which is in the sealed records of an appeals court in Washington, but it’s not clear when or whether the request will be granted.