My father, Samuel Semoff, who has died aged 75, was a medical researcher at Liverpool University for many years. But he was better known as a committed campaigner who strove for racial and social justice.

Our family moved to Toxteth, Liverpool, the day after the 1981 riots ended, and Sam threw himself into grassroots campaigns. He became well respected, particularly among the black and Somali communities. His work included the Somali Mental Health Project, editing the Toxteth Community Health Forum’s newsletter and providing welfare rights advice to Somali women. Recently he campaigned against proposals to move the Liverpool Women’s hospital from Toxteth.

A founding member of Keep Our NHS Public, Merseyside, he campaigned against the private finance initiative, in particular the Carillion Royal Liverpool development. Against much criticism from local media and public officials, he succeeded in bringing about a judicial review, which forced the hospital to rerun the consultation. Even serious illness did not deter him: he addressed a junior doctors’ strike rally while in hospital.

Sam was born in Philadelphia, Pennsylvania, the son of Jewish farming parents – his Orthodox mother, Dora (nee Levintova) and communist father, Meyer, had emigrated from eastern Europe in 1934. Sam’s childhood years were typical for a young Jewish boy growing up in 1950s America, until his father’s political leanings brought him to the attention of the FBI during the McCarthy era.

As a teenager, Sam went to live with his brother in Arizona. There he completed his education, attending Tucson high school, and eventually receiving a PhD in cell and molecular biology from the University of Arizona. He met Lillie Vaughan at Northern Arizona University, in Flagstaff, where they both attended a journalism class, and they married in 1962. Sam travelled to Britain in 1979 on a research grant from Liverpool University, later moving to the School of Tropical Medicine – part of the university – working in the electron microscopy unit.

Sam was a dedicated anti-Zionist. His view was that Jewishness “is about equality and opposition to injustice”, and he was a founding member of Liverpool Friends of Palestine. He will be remembered for his warmth, his unquenchable, battling spirit and his belief in the power of community.

Sam and Lil divorced. He is survived by me and his granddaughter, Karlaya.