Ms. Gallagher currently lives in Spain where she is a consultant to the Jesuit Refugee Service (JRS) working on advocacy and research related to international migration and refugee issues. She was the Pedro Arrupe Chair of Migration and Refugee Law at the Deusto University in Bilbao, Spain from 2002 until 2004.

Gallagher co-founded the Center for Human Rights Legal Action (CHRLA) in 1989, a non-profit organization dedicated to the promotion of respect for human rights in Guatemala. From 1992 through 1994, she was the Regional Director for CHRLA in Guatemala City, Guatemala where she and her colleagues investigated cases of human rights violations, presented complaints to the Interamerican Commission of Human Rights of the Organization of American States, and monitored and reported on the situation of internally displaced persons and the return of refugees from Mexico.

After returning to the United States, she continued human rights advocacy work with CHLRA (1994-1996), was the Legal Director of the American Immigration Law Foundation (AILF) from 1996 to 2000 and taught at the Center for Applied Legal Studies (CALS) of the Georgetown University Law Center from 2000 until 2002. She previously worked in small firms in Washington, D.C. representing clients in immigration and criminal proceedings before administrative, state, and federal tribunals.

Gallagher graduated from Temple University in 1987 with a B.A. in political science, obtained her law degree from the Antioch School of Law in 1987, and obtained an LL.M (Master of Laws - Advocacy) in October 2004.