Cox, Arthur Conor Joseph (1891–1965), solicitor and senator, was born 25 July 1891 in Dublin, younger of two sons of Dr Michael Cox (qv) (1852–1926), physician, originally of Roscommon and Sligo, and Elizabeth Cox (née Nolan). Like his father, Arthur Cox supported the Irish parliamentary party and maintained an interest in a wide range of subjects outside his chosen career throughout his life. He attended (1900–09) Belvedere College, where he often obtained first place in his class and won the Union prize for essay writing, three years in a row (1905–7). He was the first (1908) auditor of the Belvedere Debating Society and was succeeded in the post by George O'Brien (qv), who was to remain his lifelong friend. In 1909 Cox won both an RUI scholarship and an entrance exhibition to UCD, a college of the new NUI.
Working for an arts degree at UCD, then housed at 86 St Stephen's Green, he overcame an innate shyness to cultivate a reputation as a skilful and humorous orator in the Literary & Historical Society, where he befriended both Kevin O'Higgins (qv) and John A. Costello (qv). He had immense respect for both men, and they remained firm friends. The respect was reciprocal, and during their subsequent careers O'Higgins and Costello often had occasion to seek Cox's wise counsel. In 1912 Cox defeated Costello for the auditorship of the L & H by 112 votes to 63, and in the same year attained a first-class honours BA. His role as auditor meant that he was involved with UCD for a further year. He attended lectures at the Incorporated Law Society while at the same time he pursued both the LLB course, a one-year postgraduate law degree, and an MA at UCD. By the end of 1913 he had achieved first place in the LLB and first-class honours in his MA. In addition, he had become auditor of the Solicitors’ Apprentices’ Debating Society.
After university Cox was apprenticed to a solicitor, Francis Joseph Scallan, who ran a firm in partnership with his brother John Louis Scallan. On qualifying (1915) he remained with the firm as an assistant solicitor till 1920, when he formed a partnership with another solicitor, John McAreavey. The firm was called Arthur Cox & Co. and had its offices at 5 St Stephen's Green. Initially the new firm's clients were predominantly made up of those for whom Cox worked at his previous firm, and friends from his university days. Through George O'Brien he met Sir Horace Plunkett (qv), president of the Irish Agricultural Organisation Society (IAOS), a connection of enormous benefit, which saw the firm both become solicitor to the IAOS and gain a large number of clients through its membership.
Despite his relative youth, Cox was held in high esteem by those attempting to construct the apparatus of the newly independent Irish state in 1922. This was clear when he provided Hugh Kennedy (qv), law officer to the provisional government and future chief justice, with a lengthy opinion on the status of the Anglo–Irish treaty, in the context of drafting a constitution for the new state. He was conscious of the need to counter claims that the treaty did not go far enough in acknowledging Irish nationhood; and he advised that the first article of the new constitution should explicitly state that the sovereignty of the new state derived from the Irish people. This was ultimately done in the preamble of the Irish Free State constitution (1922).
In 1923 Cox was appointed solicitor to Siemens-Schuckert, the German engineering firm, and helped to negotiate the terms of an agreement with the Irish government for the construction of a hydro-electric station at Ardnacrusha, Co. Clare. In 1927 the Electricity (Supply) Act was passed, on which Cox advised. Although he experienced much success in these years, Cox was very much affected by the death of his friend Kevin O'Higgins, who was shot and died from his injuries on 10 July 1927. He visited O'Higgins on his deathbed. Arthur Cox & Co. had expanded rapidly in its early years, and in 1926 Cox and McAreavey purchased new premises at 42–3 St Stephen's Green. Four years later (1930) Cox bought his partner out of the firm.
Given his friendships with various members of the original Free State administration, and the amount of work he received from it, government work for Cox dried up when Fianna Fáil came to power in 1932. However, the protectionist corporate policies and implementing legislation of the new administration brought new opportunities. The legislation placed severe restrictions on foreign companies owning and operating enterprises in Ireland. Cox developed a reputation for assisting corporate clients to circumnavigate the restrictive laws. Along with his friend James Beddy (qv), chief executive of the Industrial Credit Corporation, he realised that foreign investment was essential to the growth of the Irish economy. He introduced many clients to Beddy, and between them they found ways to assist the firms in investing in various enterprises without breaching the law. During this period he cemented his reputation as the foremost corporate lawyer in Ireland. This was evident when James Marmion Gilmor Carroll (qv) appointed him, as one of only two non-family members, to the board of the tobacco manufacturers P. J. Carroll & Co. Cox played a key role in transforming the archaic practices of the firm by persuading Carroll to recruit Kevin McCourt as executive director. He and McCourt would later convince Carroll to employ his nephew, Don Carroll (qv). (Don Carroll played a key role in the modernisation and diversification of the firm, and in 1960 he and Cox negotiated the sale of 40 per cent of the company to Rothmans.)
Despite his reputation as a corporate lawyer, Cox also represented non-corporate clients, some of whom included well-known personalities. In 1946 he agreed to assist Hungarian film-maker Gabriel Pascal in attempting to persuade the Irish government to establish an Irish film studio, with a view to filming the plays of George Bernard Shaw (qv). He put much time and energy into trying to convince the government to provide finance for the venture, but to no avail.
In 1942 Cox was elected to the council of the Incorporated Law Society, and became president of the society for the 1951/2 term, presiding over the celebrations to commemorate the centenary of the society's charter of incorporation. In 1951 he also became chairman of the company law reform committee, which produced its report (known as ‘the Cox report’) in 1958. Renowned for his eccentricities, Cox was almost as well known for his shabby mode of dress as he was for his incisive mind and immense capacity for work. His reputation was also based on a strict adherence to discretion and confidentiality. This was clear in 1948 when his old friend John A. Costello, having been offered the office of taoiseach in the first inter-party government, turned to Cox for advice on whether he should accept the post. In 1954 Costello nominated him to the seanad.
In October 1953 the London firm of Nicholl Manisty & Co. retained him to represent the then British prime minister, Sir Winston Churchill, in a libel action brought by Brigadier Eric Dorman O'Gowan (qv), arising from comments in Churchill's The second world war: The hinge of fate. Churchill was also relying on the advice of his friend Sir Hartley Shawcross, leader of the English bar, who made several visits to Dublin to meet Cox and counsel (including John A. Costello). Cox and Shawcross believed it necessary to reach some form of settlement to avoid Churchill having to appear in court. The action was therefore withdrawn in return for an undertaking that certain corrections would be made.
Cox married (5 August 1940) Brigid O'Higgins (née Cole), widow of his friend Kevin O'Higgins. Prior to this he lived with his mother at 26 Merrion Square. He had purchased Carraig Breac in Howth in 1936, and moved there on his marriage. His commitment to his work meant that he often worked seven days a week and he therefore kept a flat on Mespil Road, Dublin, from 1940. In 1959 he sold Carraig Breac and moved to 8 Shrewsbury Road, Dublin.
On 14 February 1961 Brigid Cox died; soon after, Arthur decided to retire from his profession and study for the priesthood. He was intent on becoming a Jesuit and discussed his intentions with the then archbishop of Dublin, John Charles McQuaid (qv), who agreed to ordain him after two years of private tuition at the Jesuit theologate at Milltown Park, Dublin. On being accepted by the Jesuits he made arrangements to settle his worldly affairs by selling his home on Shrewsbury Road and leaving his practice to the existing partners. He entered Milltown Park on 15 October 1961 and was ordained just over two years later on 15 December 1963. His impact on Irish life over the previous forty years was evident by the presence at his ordination of John A. Costello, W. T. Cosgrave (qv), Seán T. O'Kelly (qv), and James Dillon (qv), among others.
Following ordination he was appointed to serve at the Jesuit mission in Monze, Northern Rhodesia (Zambia). He arrived at Monze in August 1964 and was appointed extraordinary chaplain to the local convent and hospital. On 8 June 1965 he suffered head injuries in a car accident while travelling to Namwada in Zambia. Taken to Choma hospital, he initially appeared to be relatively unscathed but collapsed and died 11 June 1965. He was found to have suffered from a cerebral haemorrhage and a fractured skull. He was buried in the grounds of the Jesuit retreat house in Chikuni, Zambia. Many of the Cox family papers are housed at the UCD archives.