The name wasn't notable. Neither was the sentence. But when Dewayne Gaffney was convicted in D.C. Superior Court and sent to prison this summer, it did not go unnoticed.

Gaffney, who was accused of lying to a grand jury in a murder case, was tried for perjury. It was the first time in nearly three years that the U.S. attorney's office took a perjury charge to trial in Superior Court, and more cases were coming.

So far this year, prosecutors in Superior Court have charged six people with the crime -- almost as many as were charged in the previous three years combined. Many prosecutors contend that the action is overdue, saying that lying witnesses have hampered or crippled their cases. But defense attorneys are fearful that perjury charges will be abused by prosecutors seeking the upper hand at trial.

Although the U.S. attorney's office has said there is no coordinated effort, the cases now proceeding through the court reflect mounting frustration among prosecutors. Perjury, they say, is pervasive in the District's criminal justice system because witnesses have come to think that they can lie without fear of punishment.

"I've always felt that we don't file them enough, nearly enough," said one experienced homicide prosecutor, who like other line attorneys is not in a policymaking role and would speak only on the condition of anonymity.

Not surprising in a city struggling with gun violence, five of the six perjury cases stem from testimony about shootings, most of them fatal.

In the city's most violent neighborhoods, residents often are reluctant to come forward with information about serious, even deadly, crimes, authorities said. Some witnesses fear retribution or do not trust police, or both. Others simply are defiant, prosecutors said.

When investigators are able to track them down, witnesses frequently are not forthcoming -- part of a code, prosecutors said, that tolerates, even encourages, lying to police, prosecutors and jurors.

U.S. Attorney Kenneth L. Wainstein, who inherited the crop of cases from his predecessor, Roscoe C. Howard Jr., said he is committed to prosecuting perjury.

"The importance of it is in making it clear to the rest of the world that if you lie in the grand jury, there are consequences," said Wainstein, who was appointed in May. "The system won't work if people think they can lie with impunity."

After winning a conviction in the Gaffney case, Assistant U.S. Attorney Denise Cheung, knowing that several other cases were in the pipeline, put together an internal primer about perjury, according to people who saw the document. Cheung, they said, wanted to give colleagues knowledge about what worked in the case -- and what didn't.

Last week, prosecutors won a perjury conviction against a witness in another case after a man whose trial had just begun pleaded guilty. Next month, two more perjury cases are scheduled for trial, and another is set for November.

Many defense attorneys said that as admirable as the pursuit of truth and justice is, it may not be well served by attacking suspected perjury so aggressively.

"Rather than changing a culture, I suspect [prosecutors] are going to drive people away who would otherwise speak to them, because they're afraid," said Ferris Bond, a veteran D.C. defense lawyer.

All but one of the pending perjury charges arose out of testimony before grand juries, and that is one reason defense lawyers are concerned. A grand jury is a panel of citizens that sits in secret to consider evidence from the government and decide whether a defendant should be indicted on charges proposed by prosecutors.

Defense lawyers said the grand jury can present an opportunity for overzealous prosecutors to exert undue pressure on witnesses by using the threat of perjury, and they fear that the spate of perjury charges is a sign that that is happening.

"I don't know how often or when or if that happens, but I know it's something that can happen," said Rudolph Acree, a former supervisor at the D.C. Public Defender Service and now a defense lawyer in private practice. "I'm not saying that prosecutors are going around trying to create that scenario, but it's possible that someone can be pushed to say something."

The lawyers worry that prosecutors can use such charges -- or the threat of them -- to pressure witnesses to tell the government's version of what took place and to discredit those who do not.

The fact that most of the perjury cases this year, including the one against Gaffney, arose months before the underlying cases were scheduled to come to trial has heightened that concern.

"It seems by bringing these cases pretrial, it has a very chilling effect on the defense bar's ability to bring in witnesses who could have observed something different from the government's theory," said Jon W. Norris, who was a lawyer for the Public Defender Service before going into private practice.

Prosecutors counter that the high standard for perjury guards against abuse and is one reason the charge is so rare. Under D.C. law, knowing that someone lied is vastly different from being able to prove that the person committed perjury.

The lie has to be material to the underlying case. It cannot be one person's word against another's; corroborating evidence is required. Finally, it has to be explicit enough to convince 12 jurors.

"If you're going to go to a jury, you have to have something that's pretty clear," said Assistant U.S. Attorney Thomas A. DiBiase, who supervises prosecutions of homicide and other major crimes in the 3rd Police District.

Prosecutors said another safeguard in bringing perjury charges before the trial in the underlying case is that a prosecutor risks undermining the larger case.

It is a calculated risk, and in the case of Gaffney, prosecutors decided it was worth it. Gaffney, 23, testified before a grand jury last year as it considered charges against Harry L. Wheeler, 21, of D Street SE. Wheeler was accused of ordering the April 1, 2003, killing of Michael Taylor, 22, who was fatally shot near First and R streets NW. Wheeler, who is scheduled to go on trial in February, suspected Taylor of stealing thousands of dollars in drug money, prosecutors said.

When Gaffney was asked whether anyone had ever spoken to him about Wheeler, he testified, "No, ma'am," according to excerpts of his testimony disclosed as part of the case. When he was asked whether he had ever told anyone that he had information about who killed Taylor, he said, "No, ma'am."

It was, the government argued, one lie after another, and at Gaffney's trial, people who know him testified that he had had conversations about Harry Wheeler and about Michael Taylor.

At least one witness testified that in talking to others about the case, Gaffney had been trying to warn them of potential danger.

The jury convicted Gaffney, but reluctantly, according to one of the jurors. "As far as the law was concerned, you couldn't do anything but vote guilty, but I didn't want to," Velma Dark said.

And neither, she said, did several other jurors, who, like her, thought that Gaffney got in over his head and didn't know how to get out. "I think that most of us felt that he shouldn't have been charged, that basically, he didn't know his rights," Dark said. "I don't feel he understood what he was into."

So unnerved were the jurors that at least one wrote a letter to the judge, and at least one showed up for Gaffney's sentencing in July before Judge Thomas J. Motley.

Gaffney, facing a prison term of as much as 10 years, asked Motley for mercy, and his attorney, Nakisha Winston of the D.C. Public Defender Service, asked that he be given no prison time. Motley gave Gaffney a year and a half behind bars.

"You don't have a right not to tell the truth in a grand jury," Motley said. "You don't have a right to not tell what you know."