Dec 4, 2006
The sentence was handed down to Lance Corporal Daniel Smith in a Manila courtroom for the rape of the woman in a van at a former US navy base.
Three other defendants, Lance Corporals Keith Silkwood and Dominic Duplantis and Staff Sergeant Chad Carpentier, were all cleared of rape.
The case had sparked strong protests from women's and left-wing groups.
About 100 protesters were outside the courthouse for the verdict.
They sang the nationalist song My Country and called for the end of the Visiting Forces Agreement that covers the use of overseas troops in training exercises.
The attack took place at the former US naval base of Subic Bay, west of Manila, in November last year.
Smith, 21, from St Louis, Missouri, had said the sex was consensual.
But Judge Benjamin Pozon said the woman was so drunk she could not have consented to sex.
He said the length of the sentence was aimed at "protecting women against the unbridled bestiality of persons who cannot control their libidinous proclivity".
Smith was also ordered to pay the defendant 100,000 pesos ($2,000) in damages.
The marines had been held in custody at the US embassy, after the US refused to hand them over until the end of the trial.
The defendants were stationed in Okinawa, Japan, but had just finished manoeuvres in the Philippines when the attack occurred.
The case created strong emotions in the Philippines, with protesters often appearing at the courtroom.
They had held placards including the phrases "Justice for Nicole," "Jail the Yankees," and "Rage Against Rape".
Nicole was the pseudonym given to the victim, now 23, in the case.