The other major area of constitutional friction was the judicial authority of the Irish House of Lords as the final court of appeal from the Irish courts. It was likewise an indication of the Westminster parliament's desire to establish its imperial superiority. It too was an established grievance before the end of the seventeenth century. For instance, in May 1698, a month after Molyneux's book appeared, the English House of Lords decided that the Irish House of Lords had no appellate jurisdiction in the case brought by William King, then Bishop of Derry, against the Irish Society over disputed land and fishing rights. The Irish were litigious and there was a tendency for defendants or plaintiffs disappointed with the verdict of the Irish House of Lords to appeal from it to the English House of Lords. Other cases and more than 20 years of friction followed, until finally in 1719/20 the British Parliament declared its supreme judicial authority over Ireland. The Declaratory Act, 6 Geo. I, c. 5 [GB] denied the Irish House of Lords the right to act as the final arbiter of appeals from Irish courts. In the ensuing outcry Swift and Robert, 1st Viscount Molesworth (1419), were among those who most strenuously objected to the act. Molesworth, the intellectual leader of Irish society in the 1720s, had been a close friend of Molyneux. Their agitation was supported by further editions of Molyneux's book published in 1719 and 1720.
Certainly, the 1720 Declaratory Act did not necessarily make for more equitable judicial administration, as the British House of Lords was not always aware of the background of cases appealed to it. For example, the 1779 case of Murray v. Bateman resulted in the British House of Lords handing down a judgment that upset an old Irish equity. The case involved a type of land lease common in Ireland but virtually unknown in England. In the early part of the century rents had been relatively static, and the country very poor. Consequently, a landlord wishing to sell his estate had difficulty in finding a purchaser able to give him its true value. This problem had been surmounted by the landlord issuing a lease renewable for ever in return for a combination of a substantial part of the value of the estate and a fixed annuity. However, the lease had to be periodically renewed and certain nominal conditions met at that time. Many of these leaseholders had become casual about their renewals; and as the conditions had not been met while land values substantially increased in the course of the century, the original owners were tempted to challenged the validity of these leases. Lord Chief Justice Mansfield had upheld the letter of the law and chaos was narrowly averted when the old equity was restored by an immediate act of parliament, 19 & 20 Geo. III, c. 30 (0897). Many Irish landlords saw advantage in the English verdict, and the remedial legislation passed by only two votes in the House of Commons and one in the House of Lords, where Lord Strangford, an impoverished peer and cleric, was reputed to have sold his legislative vote for 40 years. The Declaratory Act was repealed in 1782 and the right formally renounced in 1783. There followed a notorious bribery case, as Lord Strangford attempted to sell his judicial vote on the Rochfort–Loftus case (1256, 1801, 2088) and a wrathful parliament excluded him for ever, 23 & 24 Geo. III, c. 59 (1041)!
Until the early 1780s the twin questions of legislative independence and appellate jurisdiction remained a cause of smouldering resentment. In the first quarter of the century the British government tried to suppress the argument, but it flared up from time to time, triggering a demand for Molyneux's book. For the two decades following the 1720 Declaratory Act Swift was to be the principal torch-bearer for Irish colonial nationalism. In A proposal for the universal use of Irish Manufacture, published in 1720, he declared his own and his class's objections to British attempts to secure Ireland's constitutional dependency. This pamphlet advocated, inter alia, sanctions against English imports through an exclusive use of Irish goods. This became a recurrent theme, especially in times of political agitation or economic depression.