Born in Thatcher, Colorado and raised in Buena Vista, Colorado, Arguello grew up the daughter of a railroad worker who housed his family for a time in a boxcar. Arguello earned a Bachelor of Science degree from the University of Colorado at Boulder in 1977, becoming the first member of her family to graduate college, and then she earned a Juris Doctor from Harvard Law School in 1980. Arguello began her law career as an associate in private practice. She worked for Valdes-Fauli, Cobb & Petry in Miami, Florida from 1980 until 1985, when she joined Holland & Hart as a senior associate. Arguello was promoted to a partner at Holland & Hart in 1988. In 1991, Arguello joined the University of Kansas School of Law as an associate professor. She was promoted to full professor in 1998. In 1999, Arguello took a job at the University of Colorado, but changed her mind before ever teaching a class, choosing instead to join the Colorado Attorney General's office as a Deputy Attorney General, working alongside then-Attorney General Ken Salazar from 1999 until 2002.
Tenth Circuit nomination under Clinton
On July 27, 2000, President Clinton nominated Arguello to the seat on the Tenth Circuit that opened up when John Carbone Porfilio took senior status. Clinton previously had nominated James Lyons to the seat in September 1999, but withdrew Lyons' nomination in June 2000. Since Arguello was nominated after July 1, 2000, the unofficial start date of the Thurmond Rule during a presidential election year, no hearings were scheduled on her nomination, and the nomination was returned to Clinton at the end of his term. President George W. Bush chose not to renominate Arguello to the Tenth Circuit. Later, President George W. Bush nominated Timothy Tymkovich in 2001 to the Tenth Circuit seat to which Arguello had been originally nominated. Tymkovich won Senate confirmation two years later.
Later work
After leaving the Colorado Attorney General's office, Arguello joined the firm of Davis, Graham & Stubbs in Denver in 2003, and also served as a visiting professor at the University of Denver's Sturm College of Law in 2003. In April 2006, she took a leave of absence from Davis Graham to join the University of Colorado as its Managing Senior Associate University Counsel. She held that job until she became a federal judge.
Colorado district court nomination under Bush
On January 30, 2008, United States SenatorWayne Allard of Colorado submitted Arguello's name to the White House as part of a list of seven names for the president to consider nominating to three vacant U.S. District Court judgeships. On April 3, 2008, Senator Ken Salazar of Colorado, included Arguello's name in a list of three names that Salazar was recommending that the president nominate. Arguello's name was included as one of three that the two senators eventually jointly forwarded to the White House. On May 17, 2008, a television station in Denver reported that the White House had accepted Arguello as a Colorado district court nominee. On July 10, 2008, Arguello was officially nominated by President George W. Bush to a vacancy on the United States District Court for the District of Colorado created by the retirement of Judge Walker David Miller. On September 9, 2008, she received a hearing before the Senate Judiciary Committee. She was voted out of committee two weeks later on September 25. The Senate confirmed Arguello to her district court seat in a voice vote on September 26, 2008. She received her commission on October 21, 2008, and her formal investiture ceremony took place on December 5, 2008.
2009 U.S. Supreme Court vacancy
On May 18, 2009, Arguello confirmed to a Denver television station that she had been approached by White House intermediaries one week earlier about being considered to fill a seat on the Supreme Court of the United States. "I said 'yes,'" she told the station. "I wouldn't have gone this far if I didn't think I could serve my country in this way."
