Let me tell you about one person who decided to leak classified information by the name of Thomas Cavanaugh.
I didn't know Cavanaugh personally, but the story as I heard it through the grapevine was this...
Cavanaugh had apparently run up some rather large credit card debts with trips to the Carribean and decided he had the perfect "Get Rich Quick" scheme. He decided to sneak classified documentation outside of work and sell it to Russia. After managing to conceal two such documents and get them past the security stations where all persons are searched when leaving the building - Cavanaugh did the what any highly intelligent engineer would do to contact the KGB.
He used the Yellow Pages, and called up the Russian Embassy in San Francisco. Now the Russians happen to know that their phones are tapped, and as soon as Cavanaugh offered them the documents they hung up -- but the FBI didn't. They returned his phone call and setup a meeting where he could delivery the documents and receive payment.
When he arrived he was arrested and eventually given Two Life Sentences, one for each document.
Now I heard this story years ago and never really saw any media reports to confirm it -- but as I decided to write this Dairy I found this.... a training document from the Defense Security Service which describes the Cavanaugh Case in detail.
After copying the documents, the agents handed Cavanagh the payment in small bills. He counted it eagerly. He wanted to have monthly meetings with substantial payment each time. After they finished their business, there was a knock on the door. When they opened the door, FBI agents entered the room and arrested Cavanagh.
Through its counterintelligence operations, the FBI had learned of Cavanagh's intention to sell secrets before he reached the Soviets. The persons he met with were actually FBI agents posing as Soviets. Charged and convicted on two counts of espionage, Cavanagh was sentenced on 23 May 1985 to concurrent life terms in prison.
What Cavanaugh did, trading classified data for cash is little different than what Libby (and others) may have done - use classified data for political purposes and they should be similarly sentenced.