Eduard Johan Pieter Jorissen (1829-1912) studied in Zwolle and the University of Utrecht, Netherlands, where he took a course in theological studies. He served as minister in Kempereiland, 1854-1859, Broek in Waterland, 1859-1861 and Groningen, 1861-1868. He took a Doctorate in Theology at Groningen, 1875.

In the same year he came into contact with the Transvaal President, T.F. Burgers, who was visiting the Netherlands to recruit staff for the new Pretoria State Gymnasium. Shortly afterwards, he accepted a lecturer's post in Classics in the Transvaal, though he was persuaded on arrival in Cape Town that his theological and philosophical views would bar him from involvement in Transvaal educational affairs. On reaching Pretoria, he took his attorney's examination without any previous legal study and aided by a commission not competent in law. By 1876 he was Attorney-General.

In 1876 he drafted martial law and in 1877 the Transvaal constitution. However, his partial acceptance of the British annexation of the same year brought him into temporary disfavour with the more conservative Afrikaners, and he was dismissed from his position in the new administration. Nevertheless, he was invited to attend discussions to determine future resistance in 1879, and afterwards became linked with the cause of Transvaal independence, attending the Afrikaner leaders' conferences and travelling to the Cape legislature in 1880 with Kruger and Commandant-General Piet J. Joubert to oppose plans for a South African federation. During the armed struggle against Britain, Jorissen became a member of the Executive Council of the restored Transvaal government at the great meeting at Paardekraal on 16th December 1880 and was responsible for the drafting of a number of proclamations on the state's right to independence. He also played an active role in the peace negotiations at Laingsnek in March 1881.

After the restoration of Transvaal independence through the Pretoria Convention, 1881, Jorissen was re-appointed Attorney-General, drawing up regulations for the Supreme Court, serving temporarily as Chief Justice and Chairman of the Railways Commission and advocating a transport link with Delagoa Bay. A chairman of the Official Bank Commission, he advocated the establishment of a Dutch bank to reduce dependence on British capital, though this brought him into conflict with those who, led by the Revd. S.J. du Toit, wanted a national bank controlled by Afrikaaners. During a visit to Europe in 1883, ostensibly for medical reasons but unofficially to obtain a modification of the Pretoria Convention, du Toit and others engineered his dismissal as Attorney-General.

Jorissen became a member of the Volksraad for Pretoria in 1884, but never regained his earlier influence with Kruger. In 1886 he again travelled to Europe, eager to strengthen bonds between the Netherlands and Transvaal, and vainly attempting to become Dutch Consul in Pretoria. Returning to the Transvaal, he practised as an advocate in 1888, until the government appointed him Special Judicial Commissioner in Johannesburg, thus ending the estrangement between him and Kruger.

In 1890, as the influence of Du Toit over Kruger was waning, Jorissen was appointed a criminal judge of the Supreme Court. Three years later he chaired the commission to revise the constitution and in 1893 founded the Nederlandsche Vereeniging in Pretoria. He also codified the laws of the Transvaal in Codex van de locale wetten der Zuid-Afrikaansche republiek: eene proeve (Groningen; s.d.; 1894) and received an honorary doctorate of Laws in 1895 from [Groningen] University. However, during the Jameson Raid, 1896, he clashed with Joubert, wrongly accusing him of treachery whilst taking a harsh stance against the invaders which was not shared by Kruger.

In 1896 he undertook another journey to Europe during which he had informal discussions with the French government about a cable service between France and Delagoa Bay. Soon afterwards, it is likely that he was leader of a group of barristers oppposed to Kruger's government over the testing right during Transvaal's judicial crisis, and by 1897 the press was questioning his judicial competency. Increasingly mentally unstable during his later years, little is known of his activities during the South African War, 1899-1902. He was married to Anna Catharina Elisabeth van Eyk, with whom he had two daughters and three sons, but lost his wife in 1900 and returned to the Netherlands permanently in 1907. He was the author of several theological works, an autobiography, Transvaalsche herinneringen 1876-1896 (Amsterdam, Pretoria; s.d.; 1897) and various other publications.