* Farmers sue Chevron for $27 bln in environmental damages
* Say company responsible for contamination in 1970s, '80s
* Judge stops answering phone to avoid threats, insults
* Ex-military officer Zambrano promises a fair ruling
By Hugh Bronstein
LAGO AGRIO, Ecuador, Jan 31 (Reuters) - Judge Nicolas Zambrano often leaves work so late he has to wake up the security guard to let him out of the courthouse and onto the dark and dangerous streets of this Ecuadorean jungle town.
Zambrano -- a solidly built former air force officer with a shaved head and penetrating brown eyes -- is hearing the $27 billion suit brought against Chevron Corp by local farmers who say the U.S. energy giant polluted the rain forest with faulty drilling practices in the 1970s and 1980s.
It is the biggest environmental damages suit ever tried. The company denies the charges and wants the case thrown out over allegations that plaintiffs' lawyers engaged in fraud and other improper conduct.
The chairs and sofa in Zambrano's office are littered with 100-page makeshift notebooks full of evidence, each packet held together with white string.
"There's barely any place left to sit," Zambrano joked with Reuters during a recent visit to his chambers in Lago Agrio, a hardscrabble Amazon town near the Colombian border.
"I have about 500 notebooks to go," he said, holding his battered reading glasses in his hand and smiling. "Not much."
He has already gone through 1,500 of the packets and is widely expected to issue his verdict later this year, although he declined to comment on the possible timing of his ruling.
Investors are watching to see if Chevron will ultimately have to pay massive damages, setting a precedent that could support more big lawsuits against petroleum companies accused of polluting countries around the world.
The case also highlights the risks of doing business in Ecuador, where leftist President Rafael Correa often feuds with the private sector and has publicly sided with the plaintiffs.
But the short and compact Zambrano, who spent six years in the military before becoming a prosecutor and then a judge, said he is focused exclusively on the legal arguments at hand.
He has given up answering calls from unidentified numbers on his telephones, and has stopped looking at his e-mails altogether in order to avoid being distracted by people who may want to influence his decision.
"I never answer the telephone or my cellphone without seeing a registered incoming number, because it could be anyone calling to insult or threaten me," said the 54-year-old judge.
Threats should be taken seriously in Lago Agrio, where drug-running Colombian rebels are known cross over to spend their cocaine dollars in Ecuador's dollar-based economy and most people abide by a self-imposed nighttime curfew to stay safe.
Asked if he has received strange calls, Zambrano answered: "That's why I don't answer anymore."
The case has spawned a slew of related court actions in the United States and Europe and has been filled with intrigue.
Indigenous tribe members and local subsistence farmers say Texaco wrecked a wide swath of Ecuador's jungle by dumping drilling waste into unlined pits and leaving them to fester.
Chevron inherited the case when it bought Texaco in 2001 and says it cleaned up all the pits it was responsible for.
But the dirt just under the surface of some former waste pools still has a black sheen and carries the eye-watering stench of oil. Farmers say they cannot raise crops or livestock in these areas due to the contamination.
A documentary film organized by the plaintiffs to help support their cause turned into a liability for them after Chevron subpoenaed outtakes from the film.
The clips, which did not appear in the released version of the 2009 production "Crude," show representatives for the plaintiffs discussing tactics to pressure the court into ruling in their favor.
Chevron vows to appeal any adverse verdict. It says the trial has been prejudiced by collusion between plaintiffs' lawyers and the court-appointed expert who came up with the $27 billion damages figure. The plaintiffs deny the allegations.
The company says Zambrano has ignored evidence of government interference in the case and illegal conduct by the plaintiffs. But the judge vows that his verdict will be "just, according to the law and the principals of the constitution."
"I am working calmly, with the door shut to avoid interruptions of any kind," Zambrano said.
The bluish-green paint is peeling in the tropical humidity of the judge's office and he has shaved his head, "to stay cool, so I can think better."
He says he often works until 10 or 11 at night, long after other court employees have left. When he walks out of the courthouse he goes out alone. No bodyguards.
"It's our supreme creator who protects me," Zambrano said. "I don't have anything to be afraid of." (Additional reporting by Alexandra Valencia and Victor Gomez; Editing by Daniel Wallis and Jackie Frank)