She was invited to sit on the general council of the First International, the only woman to do so, where she engaged in debate with prominent communists including Karl Marx and Friedrich Engels.
[3] When giving a series of lectures in Keighley, Yorkshire, in September 1866 she had to compete with Henry Grattan Guinness, of the brewing family, a nonconformist evangelist who held meetings at the same time to try to counteract her influence.
[5] Writing in 1893, Annie Besant said of her, "Mrs. Harriet Law, a woman of much courage and of strong natural ability, had many a rough meeting in her lecturing days.
"[4] Some of the lectures Law gave at Cleveland Hall in Fitzroy Square in London in the 1860s were titled "The Teachings and Philosophy of J.S.
", "The Late Robert Owen: a Tribute to His Memory" and "Appeal to Women to Consider their Interests in Connexion with the Social, Political, and Theological Aspects of the Times.
"[8] In June 1867 she shared the stage at a suffrage meeting in Cleveland Hall with the American physician and woman's rights activist Mary Edwards Walker.
[7] In 1876 Law was engaged by the Lancashire Secular Union to give ten special lectures, each attended by about 5,000 people.
[9] On her lecture tours in the provinces Harriet Law did not represent the leadership of the movement, but served as a freelance speaker at the meetings of the local secularist societies.
George Holyoake, Charles Watts and Harriet Law then founded the British Secular Union, which remained active until 1884.
[17] In 1868 Marx said that the "well-known orator Mrs. Harriet Law" represented the atheist popular movement in the General Council.
She was among the signatories on the 1872 brochure The Fictitious Splits in the International in which Marx and Engels opposed Mikhail Bakunin and his supporters.
[20] After leaving the General Council, Law was elected to represent the Central Society of Working Women of Geneva at the IWA's Hague Congress in 1872, but for some unexplained reason was unable to attend.
[1] She gave the paper a broader scope, with sections that covered atheism, women's rights, Owenite co-operation and republicanism.
In July 1877 it was reported that she had engaged Cleveland Hall for another 12 months, and that she and others would talk on "The Recent Trial in Relation to Secularism.
[1] On 27 August 1868 Law argued against Karl Marx, who opposed turning the IWA into what he called a "debating club".
On 28 July 1868 she again appeared to oppose Marx, praising the positive effect of factory automation in reducing the dependence of women on men.
[33] Harriet Law has been called "a florid middle-aged farmer's daughter" who "had what some devotees of 'culchaw'[b] do not possess—a great deal of natural ability.
"[35] Eleanor Marx said she was one of the first women to recognise, "the importance of a woman's organisation from the proletarian point of view", and went on to say "When the history of the labour movement in England is written, the name of Harriet Law will be entered into the golden book of the proletariat.