The new film from Betsy West and Julie Cohen, the directors of RBG, is about Pauli Murray (1910-1985), a Black activist whose contribution to the women’s liberation and civil rights movements in the US were crucial yet sorely under-documented. Murray’s legacy as a scholar, a lawyer, a poet and a priest is so vast that it seems near impossible to force labels on a life so fully lived. Charting the numerous milestones in their fight for justice, the documentary cements Murray’s status as a pivotal catalyst for change.

It all began when Murray was refused entry to the University of North Carolina, which at the time did not admit female students. The academically determined Murray proceeded to send numerous letters to then President Franklin D Roosevelt, decrying the shallowness of his progressive image. Such an audacious, courageous act embodies Murray’s fearlessness as an activist who engaged in acts of civil disobedience decades before the were part of an organised movement. Moreover, their work as a graduate student, which interpreted the 14th amendment as applicable to people across sex and race, was instrumental in later supreme court cases on equal protection. Underneath Murray’s professional confidence, however, was the aching turmoil of gender dysphoria, which led to bouts of painful depression.

It is something of a shame, then, that this extraordinary story of an extraordinary person is told via bland film-making reminiscent of a public service announcement. Archival materials featuring Murray’s own voice prove to be the most engrossing moments, giving viewers engaging access to the character behind the achievements. Alas, these are few and far between. Still, as a tool for education about a still-marginalised figure, this is an important watch.

• My Name Is Pauli Murray is released on 17 September in cinemas and on 1 October on Amazon Prime Video.