Liu carries credentials that some conservatives love to hate -- including a leadership position in a progressive legal group and a record of opposing the confirmation of Supreme Court Justice Samuel A. Alito Jr.
But he has conservative admirers too. Liu has supported school choice as a solution to problems in urban education, and has served as faculty advisor to the California College Preparatory Academy, a public charter school. He came to the White House's attention with the recommendation of some conservatives.
If confirmed, he could be the only full-time Asian American judge on a federal appellate court. A senior administration official revealed his nomination on condition of anonymity.
In the political world, Liu is sure to be remembered as an Alito critic. When Alito was nominated to the high court, Liu co-wrote a report critical of his record on capital punishment, saying Alito's appellate opinions "show a disturbing tendency to tolerate serious errors in capital proceedings" and "reveal troubling perspectives on federalism, race and due process of law." Liu testified against Alito during his 2006 confirmation hearings.
Liu, 39, also is chairman of the board of the American Constitution Society, whose mission statement opposes the "activist conservative legal movement."
"Keeping Faith With the Constitution," a 2009 book that he co-wrote, discusses the shortcomings of "originalism," a conservative legal theory maintaining that the Constitution should be interpreted based on its 18th century framers' intent. Progressive judges tend to see the Constitution as a living document, shifting with the times, and to validate rights that they see as logical extensions of it.
Even without a possible ideological fight, the confirmation process is highly charged for Obama nominees, with Republican lawmakers stalling votes even on those whom they later support. At the moment, 26 judicial nominees await Senate confirmation, including seven to appellate courts.
But Obama's judicial choices have won strong bipartisan support on the Senate floor. Liu's supporters hope that his personal story and slightly unpredictable politics will help him win confirmation.
Liu is the son of Taiwanese immigrants. He was born in Georgia, grew up in Sacramento and has a history of public service.
Unafraid of television cameras and news interviews, Liu has a reputation as being affable and savvy. He has written several opinion pieces for the Los Angeles Times, most recently analyzing the legal issues surrounding Proposition 8, which banned same-sex marriage in California.
Given Liu's prominence in legal circles, his nomination does not come as a surprise. His name has been bandied about among candidates for the appellate court, which Obama, a constitutional lawyer, can shape as a pool for future Supreme Court nominees.
"He's as sharp as they come, with a kind demeanor and a good temperament," said Sen. Dianne Feinstein (D-Calif.). "And he's someone who has earned the broad respect of his colleagues on the left and the right."
The only Asian American serving on a federal appeals court is Judge A. Wallace Tashima of Los Angeles. But he took "senior status" in 2004, which means he hears fewer cases than his colleagues. Another Asian American, Denny Chin,has been nominated to the U.S. 2nd Circuit Court in New York, but has yet to be confirmed.
The 9th Circuit is the busiest federal appeals court in the system, reviewing about 16,000 lower-court decisions in most years. It is also the most second-guessed: Last year, the Supreme Court overturned the 9th Circuit at least in part in 15 of 16 cases it reviewed.
Liu is associate dean and a professor of law at UC Berkeley's Boalt Hall School of Law, where he has been on the faculty since 2003. He was a Rhodes scholar at Oxford University and earned a degree from Yale Law School before clerking for Supreme Court Justice Ruth Bader Ginsburg in 2000.
He worked at the Department of Education during the Clinton administration and at the Corporation for National Service, a government agency that supports community service and volunteerism. He helped launch the AmeriCorps national service program.
At Berkeley, Liu has worked on a research and advocacy project to improve the finance system for California public schools, and served as consultant to the San Francisco Unified School District. He's married and has a 2-year-old daughter.
In a recent letter supporting Liu's anticipated nomination, the director of the conservative Goldwater Institute's Scharf-Norton Center for Constitutional Litigation referred to a law review article that Liu co-wrote. In the article, Liu supported school choice as one way to improve education in urban schools. Many Democrats and progressives oppose school-choice measures, contending that they will weaken schools in struggling neighborhoods.
"It took a great deal of courage and integrity" for Liu and his co-author to take that position, Clint Bolick wrote in the letter to the Senate Judiciary Committee. "Having reviewed several of his academic writings, I find . . . Liu to exhibit fresh, independent thinking and intellectual honesty."
Times staff writer Carol J. Williams in Los Angeles contributed to this report.