Before hearing those arguments – which will attempt to sum up months of testimony - the jury of eight women and four men will hear from U.S. District Judge Sim Lake, who will give detailed instructions on what the panel can and cannot consider when it is time to hash out a verdict.
Deliberations are expected to begin on Wednesday.
Each side has six hours to summarize the case that lasted more than 14 weeks and featured 54 government and defense witnesses, including Lay and Skilling. Each side also presented mountains of documents and hours of video and audiotapes that will be available for jurors to sift through during deliberations.
Skilling, 52, testified for seven and a half days and maintained a tense civility, declaring from the outset, "I am absolutely innocent." Lay, 64, was largely combative during his nearly six days on the witness stand, snarling at a prosecutor and even challenging his own lawyer.
"I wanted the truth to come out about Enron, and elected to testify on my own behalf. I believe that my legal team and I brought out important facts about Enron and its collapse," says Lay, on his web site set up especially to comment on the trial –– in the same way that Martha Stewart set up a web site during her trial.
Responding to allegations that he deceived investors and others as to Enron's worth, Lay says he "was confident that Enron was financially strong, highly profitable and growing rapidly and we had the numbers to prove it... I failed to save the company that I helped build and loved. As I have said many times, I am devastated by this failure and its negative impact on so many lives. But failure does not equate to a crime."
Sam Buell, a former prosecutor with the Justice Department's Enron Task Force who is a visiting professor at the University of Texas School of Law, said it will be critical for prosecutors and the defense teams to tell a coherent, compelling story. The sprawling nature of the case may leave the panel looking for a big-picture view.
"A jury can't help but feel a little bit at sea. They're looking for a lifeline to pull it all together, and the trial lawyer needs to provide that to them. So, the thematics are important, and we'll hear them from both sides," Buell said.
Buell added that prosecutors will encourage jurors to see their case as a puzzle with pieces that must be viewed as a whole. The defense teams will seek to pick it apart, he said.
The government contends Lay and Skilling repeatedly lied to employees and investors by spouting false optimism about Enron's financial health when they knew bad news was brewing and that unsustainable accounting tricks had crafted illusory success in the company's final years.
The two men, who both testified, counter that no fraud occurred at Enron other than a few executives who skimmed millions from hidden scams. They say a lethal combination of bad publicity and lost market confidence fueled Enron's swift spiral into bankruptcy protection in December 2001.
Skilling faces 28 counts of fraud, conspiracy, insider trading and lying to auditors that address his actions from 1999 through his abrupt resignation after only six months as CEO in mid-August 2001. Lay faces six counts of fraud and conspiracy focusing largely on his actions after he resumed as CEO upon Skilling's departure.
The trial lacked obvious smoking guns, and boils down to whom jurors choose to believe.
Prosecution witnesses described a sinking company reliant on fraud to appear healthy. They included eight-ex-Enron executives who pleaded guilty to crimes, some who had immunity deals and others who voiced concerns that fell on deaf ears.
The defendants said those witnesses lied, made faulty judgments based on incomplete information or misunderstood what they believed to be incriminating conversations.