Miriam Bridelia Cummings was born at Thames on 15 June 1879, one of eight children of Irish-born Matthew Cummings, a carpenter, and his Scottish wife, Annie Cunningham. The couple solved the problem of their different religious allegiances by bringing up their two sons as Protestants and their six daughters as Catholics.
After attending Thames and New Plymouth high schools, where she excelled, Miriam Cummings became a pupil-teacher in 1896, first at New Plymouth Central School and then at Kauaeranga School, Thames. Tall and rather angular, she had dark colouring and an intense gaze. At the age of 19 she began teaching at Taumarere Native School in Northland, later moving to Pakaru School. Boarding with a part-Maori family at Pakaru, she became deeply interested in Maori culture and welfare and fluent in the language. She kept in touch with former pupils all her life.
Miriam's teaching career was interrupted by the birth of a daughter in Auckland in 1905. She also seems to have spent time working as a housemaid in Rotorua, where, on 10 June 1908, she married Peter Soljak, a restaurant keeper. Recently arrived from Dalmatia, Soljak had little education and spoke imperfect English, but was practical and willing to turn his hand to anything. The couple set up house at Rotorua, then Cambridge. Miriam resumed her teaching around 1910 at Pakaru, Northland, where her skill working with Maori children was so valued that she was provided with day care for her growing family. Meanwhile, Peter worked on a bridge-building project near Kawakawa. When the birth of her fourth child in 1912 ended Miriam's teaching career, the couple moved to Tauranga where Peter dug ditches, built stone fences, and transported flax to the rope works and shells to the lime works. The family struggled financially and moved constantly.
For Miriam Soljak the spur to political activism came with the First World War. She was outraged to learn that by marrying a foreigner she had forfeited her British nationality. Moreover, although Peter had migrated partly to escape conscription to the army of the hated Austrian Empire, the couple were classed as Austrian enemy aliens, and were forced to register with the police and endure restrictions on their possessions and activities. When Miriam's seventh and last child was due, she was refused a bed in the nursing home. The registration of aliens was maintained after the war until 1923; forced to comply under threat of prosecution, Miriam insisted that her registration be marked 'under protest'.
When the family moved to Auckland in 1920, Miriam Soljak found a friend and political ally in Emily Gibson, a member of the Auckland Women's Political League. This organisation and the Women's International League had amalgamated as the Women's International and Political Leagues, and in 1925 became the Auckland women's branch of the New Zealand Labour Party. Through this channel Miriam succeeded in putting independent nationality for women firmly on the New Zealand Labour Party agenda. In 1927 Labour politician Peter Fraser sent her, 'with compliments', a bill he was introducing to enable a woman marrying a foreigner to retain her nationality. In fact the New Zealand Parliament could not alter the law except as it related to civil rights in New Zealand because the law governing British nationality applied throughout the empire.
Miriam Soljak's political style was confrontational. In 1926 she helped organise a protest outside the Auckland Town Hall against withholding the unemployment benefit from women workers and clashed sharply with the mayor, who had tried to adopt a conciliatory line. Later, as one of a deputation of the New Zealand Section of the Women's International League for Peace and Freedom, she refused to accept the claims of the minister of health, A. J. Stallworthy, that unemployment was not a problem for women, that there were no homeless women, and that women should rely on private charity. In 1931 she calculated that there were 10,000 unemployed women in Auckland alone. That year she worked on the Auckland Unemployed Women's Emergency Committee but resigned when she realised its funding was sufficient only to maintain a register of unemployed women.
As vice president, president and secretary of the Auckland women's branch of the Labour Party in the late 1920s, Miriam Soljak was involved in a wide range of contemporary feminist issues, including the campaigns against compulsory military training and the high rate of maternal mortality, and for disarmament, motherhood endowment, child welfare and sex education. She developed a reputation as a trenchant freelance journalist and a compelling public speaker, and worked with urban Maori, explaining Labour's policies to them in Maori. In 1930 her fruitful association with the branch ended abruptly. Soljak had written a letter protesting against the searching of homes of Samoan independence leaders, which was published in the Samoa Guardian in May 1930. She had signed the letter using her official title, and had made other public statements as secretary which she refused to withdraw. She was censured, and her nomination for life membership was formally expunged from the minutes.
For a time in the 1930s she associated with members of the Communist Party of New Zealand. She also became involved with other radical organisations. Angered by a priest whose advice to her on family limitation was 'submit or abstain', she broke with the Catholic church and wrote a series of letters under the pseudonym 'Zealandia' to the New Zealand Herald in favour of contraception. In 1934 she raised the issue of birth control at the first Working Women's Movement Conference in Wellington, and subsequently the Sex Hygiene and Birth Regulation Society was established. She became a foundation member of the Auckland branch of the New Zealand Family Planning Association in 1940 and joined the Rationalist Association and Sunday Freedom League.
In 1934 Miriam Soljak visited her friend and fellow socialist, the writer Jean Devanny, in Australia. Assisted by a reference from the chief announcer at Auckland's radio station 1YA, which described her as a 'well known lecturer and social worker' who had broadcast on several occasions, she obtained radio work while she was there. Through her association with the Australian feminist Jessie Street, she helped bring the Australian Women's Charter Movement, which sought unity between women's organisations, back to New Zealand.
In 1936, with financial help from her family, Miriam Soljak achieved a long-held ambition to travel to London. She found the question of women's nationality a leading concern of British feminists. At the 1937 conference of the British Commonwealth League, an influential women's organisation, she described how New Zealand's legislation on women's nationality could apply only within New Zealand. Her own husband's naturalisation in 1928 had not changed her national status outside New Zealand and she had had to travel on an endorsed passport. She was accorded the honour of moving the annual resolution reaffirming 'the right of a married woman to her own independent personal nationality on the same terms as a man'. After her return to New Zealand, Peter and Miriam Soljak, who had been separated for some years, ended their marriage; to Miriam's chagrin, even the divorce, which was finalised in October 1939, did not restore her nationality.
In the late 1930s Miriam Soljak contributed hard-hitting articles to the new left-wing periodical Woman To-day. In 1939, for example, she was sharply critical of the admired Social Security Act 1938, because of its disregard for wives, who were treated as mere appendages of their husbands, and its discrimination against unmarried mothers, who were ineligible for the family allowance. In another article she made a passionate plea for 'militancy' in pursuit of peace. During the Second World War she continued her peace activism through the New Zealand Section of the Women's International League for Peace and Freedom, and at the cessation of hostilities settled with a war-wounded son in Auckland.
The end of the war also saw the demise of the British Nationality and Status of Aliens Act 1928, in favour of a series of interlocking nationality acts in the Commonwealth countries. Miriam Soljak's nationality of birth was finally restored to her in 1946; ironically, since the act was retrospective, she was deemed never to have lost it. She made her peace with the Labour Party, rejoining and eventually receiving an award for long service.
Miriam Soljak died, aged 91, on 28 March 1971 at Auckland. A New Zealander through and through, she asserted her nationality and championed the cause of urban Maori and working-class women fearlessly and with total commitment.