After the prosecution spent more than two weeks calling witnesses and presenting evidence in the criminal case against former Jack Abramoff associate Kevin Ring, the jury may have been surprised to find that the defense would not call any witnesses and Ring himself would not testify.

Though jurors are always instructed against drawing inferences from a defense decision not to call witnesses or a defendant's decision not to testify -- since it is the prosecution's legal responsibility to prove guilt -- the defense's apparent lack of a case can have an impact in the real world, legal experts say.

"The jury sees Mr. Ring sitting in the courtroom every day, and yet they don't hear from him," said Marc Elias, an attorney with Perkins Coie who specializes in ethics and white collar criminal matters. The jurors "are human beings. They listen to jury instruction, but you can never be sure."

Ring's attorneys, Andrew Wise and Timothy O'Toole, expressed frustration in court because witnesses they wanted to call, who had worked in the office of former Rep. John Doolittle, R-Calif., invoked their Fifth Amendment rights. They said those witnesses -- former Doolittle staffers Peter Evich and David Lopez -- would have given crucial details about Ring's relationship with Doolittle's office.

Before joining Abramoff's lobbying team, Ring was a staffer in Doolittle's office, and prosecution witnesses in the trial described Doolittle as Ring's main "champion" on Capitol Hill.

"None of the speakers are here, and we're trying to do what we can to get some context in front of the jury," O'Toole said during trial proceedings.

The defense also wanted to call David Ayres, who was chief of staff to former Attorney General John Ashcroft, but both Ayres and his wife, Laura, invoked the Fifth Amendment to avoid testifying. The prosecution alleged that Ring gave Ayres tickets to the 2002 NCAA tournament after gaining his assistance in obtaining a $16.3 million federal grant for the Mississippi Band of Choctaw Indians, a "Team Abramoff" client, to build a jail.

During a hearing earlier in the trial, the defense disputed the number of NCAA tournament tickets that Ayres received.

"That's not right, and that's not what [Ayres] would have said if we could have called him," Wise said. "That's why this is a problem... Evidence would have shown, if he testified, that he did not ask Mr. Ring for [an additional] ticket."

Determining the number of tickets was crucial, the defense argued, because the value of one ticket was not above the disclosure threshold for an executive branch official -- meaning that Ayers' concealment of the gift would not then have been illegal. This detail, they claimed, was necessary in determining whether Ring's gift itself was illegal.

"The bind that the Ring defense team finds themselves in is that there are witnesses they would like to call," Elias said. "That does make it harder on them because presumably those witnesses would help Ring."

To encourage potential witnesses to speak freely instead of invoking the Fifth Amendment, the Department of Justice could have offered immunity; some individuals related to the investigation were granted immunity, but it was limited only to interviews with the Department of Justice.

That did not come as a surprise to legal experts, as immunizing the defense's witnesses does not benefit the government's case.

"The government is not going to immunize anyone in this case," prosecuting attorney Nathaniel Edmonds said in court.

But despite the defense's frustrations with the Fifth Amendment invocations, the lack of witnesses may not hurt their case, Elias pointed out. The jury may see it as a sign that the prosecution has not presented enough evidence.

"As the defense lawyer, you are trying to convey that the government simply failed to prove much," Elias said. The jury may see the defense's lack of witnesses as a signal that "the trial has gone on long enough, therefore [they're] not going to take up any time putting up any witnesses because the government hasn't proved their case."

The defense affirmed that view in its motion for acquittal last week. Defense lawyers in criminal cases typically submit a motion for acquittal after the prosecution has finished presenting its evidence.

"No percipient witness... testified about Mr. Ring's relationship with the office of Congressman John Doolittle, even though that relationship formed the basis of many, if not most, of the government's accusations against Mr. Ring," the defense attorneys wrote in the motion.

"None of Mr. Ring's co-workers [who testified]... could describe a single corrupt act that Mr. Ring had taken with respect to public official [sic] or had virtually any percipient knowledge of how Mr. Ring interacted with public officials," the motion continued.

In rebutting the acquittal motion, the prosecution countered that abundant evidence was given to the jury on which to base its decision.

"In over two weeks of testimony, the jury has seen and heard significant evidence of Defendant's criminal acts," the prosecution wrote. "Based on the Defendant's own emails, the jury has seen sufficient evidence to determine that the Defendant conspired to corrupt public officials."

The defense and prosecution are expected to present concluding arguments today, and after the jury reaches its decision, the defense will find out if and how those Fifth Amendment-pleading witnesses may have influenced its case.

"It can have an impact, but it's part of the system and it's something the defense will have to deal with," Elias said.