Lying about a crime, the accusation against I. Lewis "Scooter" Libby, has itself been a crime since the time of Hammurabi.
Then, it was punishable by death. Today, perjury is punishable in federal courts by a fine and up to five years of prison for each count.
Then and now, the theory has been essentially the same: If people are allowed to lie during the investigation of a crime, the crime cannot be proven. It may go unpunished or an innocent person might be wrongly punished.
That is why perjury has never required proof of an underlying crime. Without access to the truth, there may be no way to show the underlying crime. (A perjury indictment unaccompanied by a charge of an underlying crime remains, nonetheless, controversial because critics sometimes see it as the product of a failed probe.)
Perjury, the Supreme Court has said, is "an obvious and flagrant affront to the basic concepts" of justice.
To prove a charge of perjury, according to the Department of Justice handbook for prosecutors, the government must at least show:
*That the testimony was given under oath.
*That it was false and that the accused knew it to be false.
*That it concerned a matter that was "material" to the crime being investigated.
"Materiality" has been defined by the courts as anything "capable of influencing the tribunal on the issue before it."
In the Libby case, the tribunal was the federal grand jury and the issue before it was the leaking of the name of a covert agent of the Central Intelligence Agency.
The crime of making "false statements," which Libby was also charged with, does not require lying under oath. Rather, it punishes anyone who knowingly "makes any materially false, fictitious or fraudulent statement or representation" in "any matter" being investigated by the federal government.
In today's indictment, that accusation was applied to Libby's conversations with special agents of the Federal Bureau of Investigation and "other government officials."
In any prosecution of lying allegations, "materiality" is crucial. The Libby indictment described as material such matters as "the manner and means by which" Libby learned that Valerie Plame was employed by the CIA, whether and when he disclosed that information and whether he knew the information was classified.
Prosecutor Patrick Fitzgerald will have to prove the lying charges in order to prove the obstruction of justice charge, because the obstruction charge revolves around the lies Libby allegedly told.
Obstruction of justice means "knowingly and corruptly" attempting to influence or impede the grand jury investigation, in this particular indictment, by lying.
Obstruction is a "broader crime," said Wayne State University Law Professor Peter J. Henning.
In the Libby case, the obstruction charge involves not just lying to investigators but an overall "endeavor" that included comments made by Libby to journalists, among them Tim Russert of NBC, Judith Miller of the New York Times and Matthew Cooper of Time magazine.