Nourse was born in Dunedin, Florida and received her Bachelor of Arts from Stanford University in 1980 and later received her Juris Doctor from the University of California, Boalt Hall School of Law in 1984.
Nourse's first employment was as a waitress at Cafe Meursault in Palo Alto, California in 1980. From 1980 through 1981 she worked for the Center for the Study of the California Economy as a research assistant. In 1982, Nourse took a position as a summer associate with the firm of Dorr, Cooper & Hays in San Francisco. In 1983 she worked for Steptoe & Johnson as a summer associate in Washington, D.C. Her summer associate position in 1984 was with the law firm of Simpson, Thacher & Bartlett in New York City, New York.
After graduating from law school, Nourse clerked for Judge Edward Weinfeld of the United States District Court for the Southern District of New York in 1984 and 1985. During 1985 to 1987 and the winter of 1988, she worked in for the law firm of Paul, Weiss, Rifkind, Wharton & Garrison. In 1987 she worked as an assistant counsel on the United States Senate Committee to Investigate the Iran-Contra Affair.
During 1988 to 1990, Nourse was an appellate attorney with the United States Department of Justice working in the civil division. From 1990 to 1993, she worked as counsel and special counsel for the United States Senate Judiciary Committee and was heavily involved in writing the Violence Against Women Act (VAWA). She did this work under then-Senator, now Vice President, Joe Biden. This generated national controversy when Biden attempted to claim he was the author of VAWA.
Her historic battle to uphold VAWA is documented in many books, including "Equal: Women Reshape American Law" By Fred Strebeigh. In this book she was included alongside Supreme Court Justice Ruth Bader Ginsburg as a woman who had a history-changing effect on the law.
From 1996 to 1997, Nourse was a visiting professor of law at the University of Maryland School of Law. During the fall semester of 2002, she was a visiting professor of law at Yale Law School and taught law at New York University School of Law in the spring of 2003. From 2008 to 2010, Nourse was the LQC Lamar Professor of Law at Emory University School of Law in Atlanta.
On January 22, 2010, United States Senators Herb Kohl and Russ Feingold forwarded four names to the Obama White House for consideration to fill the vacancy on the Seventh Circuit Court of Appeals created when Judge Terence T. Evans assumed senior status. Nourse was recommended along with District Court Judge Lynn S. Adelman, Richard Sankovitz, and Dean Strang. On July 14, 2010, Obama nominated Nourse to the vacancy. Her nomination was returned to the President on December 17, 2011, pursuant to the rules of the Senate.
Nourse is the daughter-in-law of United States federal judge Richard D. Cudahy who is a currently on senior status from the United States Court of Appeals for the Seventh Circuit.