Chief Justice John Roberts and the other justices explored whether the federal "honest services" law -- which targets fraud through the denial of "the intangible right of honest services" -- was too vague, SCOTUSblog.com reported.
The case has implications not only for Skilling, but for others charged under the law, including former Illinois Gov. Rod Blagojevich and jailed media baron Conrad Black.
Skilling lawyer Sri Srinivasan suggested that the way the Justice Department was interpreting the law it would cover any lie that any worker told in the workplace about his job performance, the report said.
The justices also explored extensively whether the judge in the Houston Enron trial did enough to ensure a fair jury was chosen, SCOTUSblog said. Justice Stephen Breyer appeared to be most bothered by the jury selection, which took only five hours.
Skilling was convicted in 2006 because of his actions in Enron's collapse, and is serving a 24-year, 4-month sentence.
The Supreme Court should hand down a ruling in the case before retiring for the summer.