Lucy Lawless takes part in a Greenpeace protest in New Zealand on February 24, 2012. Credit: Greenpeace/Splash News

Legal trouble for the warrior princess!

Lucy Lawless has pleaded guilty to trespassing an oil drilling ship in New Zealand this past February. The Spartacus and Xena: Warrior Princess actress, 44, faces up to three years in jail for the move -- part of a protest with six other Greenpeace activists.

Lawless and the group boarded the ship and wouldn't budge for four days; they were arrested Feb. 27. The oil-drilling ship was bound for the Arctic, and Lawless and company aimed to raise awareness about the negative effect of Arctic oil drilling -- which is said to speed up global warming.

The New Zealand actress is to be sentenced in September.

Shortly before the February arrest, Lawless told Us Weekly: "This chapter has ended, but the story of the battle to save the Arctic has just begun. . .Seven of us climbed up that drill ship to stop Arctic drilling, but 133,000 of us came down."

"We will continue to stand in solidarity with the communities and species that depend on the Arctic for their lives until Shell cancels its plans to drill in this magical world, and makes the switch to clean, sustainable energy."