[4] She received a Reginald Heber Smith Community Lawyer Fellowship to work with battered women in Southwestern Virginia (1980–1981).
After doing poverty law working for Legal Services in Virginia for four years, Oppenheimer returned to California and started her own firm representing plaintiffs in employment discrimination suits, including sexual harassment cases.
With her law partner Leslie Levy, between 1989 and 1991 Oppenheimer represented tenants in the case against Fairfield North Apartments and their apartment manager, reaching an at the time unprecedented settlement for sexual harassment in housing.
[6] Later she moved to mediation and prevention of harassment and investigated Equal Employment Opportunity complaints.
Oppenheimer served as administrative law judge at the California Unemployment Insurance Appeals Board from 1992 to 2011.
In 2017, the California State Senate faced allegations of having a work environment with a pervasive culture of sexual harassment.
[8] Oppenheimer was invited as an expert to address the meeting of the State Senate Joint Committee on Rules and Subcommittee on Sexual Harassment Prevention and Response that was discussing a change in the system to deal with sexual harassment complaints.
In 2024, the Association had over 2000 members and chapters in Australia, Canada, New Zealand and South Africa.