At the height of the Watergate scandal, Alex Arriaga watched the news on television at dinnertime, wondering why President Richard M. Nixon was resisting taking a lie-detector test if he was telling the truth.

In her first political and moral act, she wrote Nixon a letter urging him to take the test -- and please, she said, don't fire my father, a Berkeley professor whom she imagined to be vulnerable to presidential anger. Arriaga was 8 years old at the time and in third grade, with a devotion to dance lessons.

The upbringing and career of Arriaga, now 38 and director of government relations at Amnesty International USA, have thrown her into the heart of human rights work. She joined Amnesty at the end of last summer, just before the shock of Sept. 11. Since then, the petite woman has been gliding through the halls of Congress with the grace of a ballerina, pondering how to protect rights in an age of terrorism.

"What does it mean to seek justice, and how do you build a future and go forward from here?" she asked. She and other activists have seized on the issues of military tribunals, secret trials and the legal rights of the Taliban and al Qaeda prisoners being held at Guantanamo Bay in Cuba. She was closely involved in the negotiations that got access to the prisoners for the International Committee of the Red Cross and is now seeking the same for Amnesty.

"There is a logic to promoting human rights as a form of promoting long-term national security," said Arriaga, who calls herself a "pragmatic idealist."

The daughter of an Argentine father and a Chilean mother, Arriaga was born into a family that has experience with political oppression going back generations.

Early in the 20th century, her mother's parents fled what is now Turkey for Chile so that Arriaga's grandfather would not have to serve in the Ottoman Empire's army, which mistreated Jews and often positioned them on the front lines in World War I. She has Spanish ancestors who sought refuge in Greece and Turkey following the Spanish Inquisition.

Her parents came here from their home countries, which were politically turbulent at the time, to teach and study at Berkeley, and Arriaga grew up in the United States, on both coasts.

"Maria Alejandra," as her parents named her, felt she was protected as a U.S. citizen, but on trips to her parents' home countries as a girl, she became aware that others were not so lucky.

In Chile, during the years of military dictatorship, she recalls the din of banging pots and pans of protesters, sandbags surrounding machine guns at street corners and buses exploding when gunfire hit their fuel tanks. "There was this over-arching sense of fear and intimidation, of not knowing who your friends are," she recalled.

Despite a budding interest in human rights, Arriaga contemplated a career in dance. At age 18, she won a summer scholarship with the Joffrey Ballet in New York, auditioned for a longer position and got it. After a year of dancing seven hours a day, living on a 450-calorie diet and fasting on weekends, Arriaga decided she missed her friends, reading and having the energy to do other things.

So she entered the University of Virginia, taking up Latin American and Russian studies and studying Russian and Portuguese,

Out of college, Arriaga got a job on the Hill with Rep. Tom Lantos (D-Calif.), working with his wife, Annette, who helped found the Congressional Human Rights Caucus. "I watched her grow and take hold of a very complicated job," said Annette Lantos. "When congressmen came to her with a problem of one of their constituents, she would organize hearings, send out letters. . . . She was effective as a spokeswoman for human rights and in activating those who had the power. For her, it was not a job, but a mission."

Tom Lantos went further: "We are just convinced she will be one of the major human rights figures in the country."

In 1995, Arriaga was hired as an adviser to John Shattuck, then assistant secretary of state for democracy, human rights and labor. "She has drive, and a clear focus, and the ability to take conversations in Congress and State and interpret them to develop strategies for achieving realistic objectives for human rights," Shattuck, now chief executive of the John F. Kennedy Library and Foundation in Boston, said in a telephone interview. "She made us do things we otherwise would not do."

Arriaga traveled to Bosnia, the one place she admitted being afraid of, as part of the State Department's task force there.

When Arriaga was asked to work in the office of President Bill Clinton's special envoy to the Americas, Buddy MacKay, she jumped at the chance. "She is quite ambitious and talented," MacKay said. "I would rather have a hard charger who sometimes needs to be reined in than someone you constantly have to push."

That job ended with Clinton's departure from office, and after a five-month stint with the Inter-American Dialogue last year, she was offered the government relations job at Amnesty. "This is what gets me excited and what I feel matters," Arriaga said.

The United States, she said, should expose the crimes of terrorists and demonstrate that "theirs is not a cause but a crime against hundreds and hundreds of individual victims." But at the same time, she said, it must respect the rights of its prisoners.

In her view, "it is very dangerous for the United States to have a go-it-alone attitude and set its own rules. The Bill of Rights refers to all people, and the United States is a precedent-setter for other countries.

"We have to be consistent, especially in times of crises," she said. "It takes a special kind of leadership."

Alex Arriaga joined Amnesty International USA last summer and is director of government relations.