The Supreme Court decision, which held that federal appellate courts can presume that any sentence within sentencing guidelines is reasonable, made it less likely that Libby's sentence would be overturned on appeal, and may have played a role in Bush's decision to commute his sentence, which was within federal guidelines.
'More Serious' for a Public Official
Nora Demleitner, interim dean at Hofstra University School of Law and co-author of a textbook on sentencing law, said that Libby's position in government distinguished him from private citizens like Stewart and Kim, and made a tougher sentence more appropriate. "It's much more serious when a public official is involved," she said.
"Judges take obstruction of justice most seriously," Demleitner said. "These charges generally carry substantial sentences — and rightfully so."
Bowers added that the fact that Libby's case involved a complex investigation into a serious national security issue could explain the difference in sentences. Lying to investigators can be more damaging to complex investigations, he said.
"They're trying to determine a variety of potential criminal conduct with multiple suspects, so it's more imperative that people cooperate," Bowers said. "Combine that with Libby's position of trust, and that could provide some enhancement for the sentence."
Berman said courts typically will not lower an obstruction of justice sentence because of a defendant's family circumstances or history of public service.
And while a 30-month sentence may seem harsh to some, John Barrett, a former prosecutor on the Iran-Contra case, said the judge was following the sentencing guidelines. "This is standard federal sentencing.
"For many people, this may have been the first time they are acquainted with the fact that this is the way federal laws work," Barrett said.
With reporting by Lauren Pearle and the ABC News Law & Justice Unit.