On April 4, 1793, Prince Augustus Frederick (later the first Duke of Sussex) secretly married Lady Augusta Murray at a hotel in Rome. Although it was a love match, their nuptials would ignite a legal firestorm that gave rise to a legal legacy that endures to this day.
Born in 1773, Prince Augustus Frederick was the ninth child of George III and Charlotte of Mecklenburg-Strelitz. Asthma prevented him from embarking on a military career like his brothers, so in 1786 he went to study at the University of Göttingen in Germany. He remained in Europe for several years, and in late 1792 he traveled to Italy for his health.
While in Rome, Prince Augustus met the Countess of Dunmore and her family, and he developed a special bond with one of the Countess’ daughters, Lady Augusta Murray. The two quickly fell in love, and after four months of courtship, the Prince proposed to Lady Augusta in secret. At first, she refused, citing the difficulties that their marriage would cause the Prince, but he continued to profess his love for her. She had a change of heart, and on March 21, 1793, the two lovers signed a contract in which they solemnly promised to marry one another.
But the couple faced a difficult path to the altar. The couple were Protestants, yet they were trying to marry in the capital of the Papal States. Local law made no clear provision for the marriage of Protestants, and Catholic priests could not officiate at Protestant marriages, either.
Roman law wasn’t their only problem. As a descendent of George II, Prince Augustus was subject to the provisions of the Royal Marriages Act 1772, which meant he needed to obtain his father’s consent before marrying. If he ignored the Act, the clergyman who officiated at his wedding (and, in theory, anyone else in attendance) would be liable to imprisonment and the loss of all their property.
Given the legal situation, the Prince believed that his best bet was to be married by a random Protestant clergyman. Both he and Lady Augusta scoured Rome for a suitable candidate, checking foreign seminaries and even making inquiries among the British expatriate community in Livorno.
Unable to find a stranger willing to officiate, the Prince turned to the Rev. William Gunn. While Gunn had the advantage of being an Anglican priest, he was also personally acquainted with the Prince, and he knew the trouble he would be getting into if he married the couple. Not surprisingly, Gunn tried to dissuade the Prince from going ahead with the marriage, and when his words failed to sway the Prince, Gunn stood his ground and refused to take part in the ceremony.
But the lovers would not be thwarted. They decided that their best hope of getting Gunn on board was to take him by surprise and, in the words of the State Trials reporter, “overcome his scruples by unexpected importunity.” On April 4, Lady Augusta asked Gunn to call on her at her hotel; when he arrived, the Prince burst in and with “entreaties of the most urgent kind,” begged the priest to reconsider his refusal. Gunn’s resolve waivered, and after securing a solemn promise from the couple to never divulge his name, he married them on the spot without any witnesses present.
Upon returning to the United Kingdom, the couple went through a second marriage ceremony at the parish church of St. George, Hanover Square. According to the Prince, this was done “for greater security, and not from an apprehension of the first [wedding] being insufficient.”
It was a perilous move. The simplest way for them to marry would have been to obtain a marriage license from an archdeacon, bishop, or archbishop of the Church of England, but aside from the fact that the Prince had violated the Royal Marriages Act, he was also too young to obtain a license without parental consent under normal marriage law. The only other option was to marry after the reading of banns. Under this procedure, a couple could wed once their parish priest had given public notice of their plans on three separate Sundays. But the banns would have to include the couple’s name, which had the potential to jeopardize the whole undertaking. The couple’s solution was to use their true names but omit their titles; so as far as the parishioners of St. George’s were concerned, it was simply the marriage of Augustus Frederick and Augusta Murray. Once again, fate seemed to be on the couple’s side, and they married for a second time on December 4, 1793.
Their luck soon ran out. The King and the Government were not amused when they learned of the couple’s union. The Privy Council launched an inquiry into the matter, but the proceedings soon took on an air of absurdity. The Lord Chancellor tried to show that the Prince had been taken in by a scheming older woman, but when questioned about her daughter’s age, the Countess of Dunmore professed ignorance. The clergy of St. George’s were hauled before the Council as well. The Council wanted to know why the clergymen didn’t notice the Prince’s name on the banns, but they were told that there were several men called ‘Augustus Frederick’ within the parish. The Council proceeded to berate the clergy and officials of the church for failing to confirm that the couple were truly residents of the parish (without a marriage license, you could only marry in your local parish church). The clergy insisted that they had done their job perfectly well, which spurred the Lord Chancellor to demand that the Attorney General prosecute everyone involved with the “abominable marriage.”
While no criminal proceedings were ever brought, there marriage itself was soon under attack. In January 1794, the King’s Proctor sought to have the marriage annulled in the Consistory Court of the Diocese of London. The matter was transferred to the Archbishop of Canterbury’s Court of Arches, which nullified the marriage on July 14, 1794.
Despite no longer being husband and wife, the Prince continued to live with Lady Augusta for many years. They had two children together: Augustus Frederick d’Este and Augusta Emma d’Este. They ultimately separated in 1801, and the King bestowed the titles of Duke of Sussex, Earl of Inverness, and Baron Arklow on his wayward son. In 1831, a year after Lady Augusta’s death, the Duke married again, this time to Lady Cecilia Letitia Buggin. This marriage also contravened the Royal Marriages Act, but this time the authorities made no effort to annul it, and the couple was left in peace.
Following the Duke’s death in 1843, Augustus Frederick d’Este attempted to claim the Dukedom of Sussex. As is typical in peerage cases, Queen Victoria referred the matter to the House of Lords on August 22, 1843, and the House in turn referred the matter to their Committee for Privileges, assisted by senior judges. At issue was whether or not the marriage of the Duke of Sussex and Lady Augusta Murray was valid, despite the fact it contravened the Royal Marriages Act.
The Privileges Committee met to consider the matter starting on June 7, 1844. In order to establish the marriage’s fundamental validity, d’Este’s counsel argued that the Prince had taken the only course available to him since Roman Catholic priests wouldn’t marry Protestants and local laws only recognized marriages conducted by the Roman Catholic Church. They compared it to a foreign marriage made at a place where no other form of marriage was available. Alternatively, they suggested it should be accepted as a contract of present relation “as if made in a desert island where no laws exist, and where the solemn and declared intentions of the parties must from the necessity of the case constitute the marriage.”
D’Este’s lawyers also argued that the Royal Marriages Act only applied to marriages contracted within British territories. They noted that many descendants of George II lived abroad, and it would be absurd to expect them to obtain the consent of the British monarch for their marriages. And because the Act created a crime as well as an incapacity, they contended that it needed to be construed strictly in line with other penal statutes. “Is the offense created by the Royal Marriages Act to receive a wider construction than the crime of treason?” asked Sir Thomas Wilde. He also highlighted the fact that there were a number of practical impediments preventing the Act from being enforced broadly. For example, although the Act required the Sovereign’s Consent to the marriage to be set out in the marriage license and the register entry, there was no way to do that in the case of a marriage contracted overseas.
The Committee then called for evidence proving the marriage. D’Este’s lawyers attempted to introduce the Duke’s will as evidence, but the Committee declined to admit it since it was written after the Court of Arches’ judgment nullifying the marriage. Next, the lawyers introduced a declaration by the Rev. William Gunn. Gunn had been reluctant to testify in previous proceedings because he feared exposing himself to the penalties of the Royal Marriages Act, which, as the Lord Chancellor, Lord Lyndhurst, observed, cut against d’Este’s argument that the marriage didn’t actually violate the law. The fact that Gunn was dead by that point also complicated matters. Ultimately, the Committee declined to admit his declaration.
Next, the Rt. Rev. Nicholas Wiseman, a Roman Catholic bishop and Coadjutor to the Vicar Apostolic of the Central District testified regarding Roman Catholic marriage law. Although their canon law made no explicit provision for the marriages of Protestants, in his view, the Duke of Sussex’s marriage would be valid. A debate ensued about the best method of answering questions about foreign law. Lord Campbell argued that texts were preferable to witnesses, who might be mistaken or biased. However, Lord Brougham observed that a text alone wasn’t sufficient since English courts wouldn’t necessarily be equipped to interpret a foreign law book. The Attorney General intervened to ask Wiseman to clarify his credentials, and Wiseman admitted that he hadn’t served on any Catholic tribunals that dealt with marriage law. However, he had studied canon law, albeit informally, and as a bishop, he was responsible for arbitrating such questions. The Attorney General still objected to his evidence on the grounds that he wasn’t a Roman Catholic canon lawyer, but Lord Lyndhurst argued that Wiseman’s office gave him sufficient authority, and the Committee agreed. D’Este’s counsel also called a Jesuit to give evidence, but while he had gone through formal training in canon law, the Committee deemed him ineligible since he ultimately had no more knowledge of the law than any other parish priest.
A few days after d’Este’s lawyers summed up his case, the judges gave their opinion to the Committee. Sir Nicholas Tindal, Chief Justice of the Court of Common Pleas, spoke on behalf of his brethren. He dismissed the central contention of d’Este’s counsel, observing that:
[I]t is scarcely supposable that the Legislature should have provided the minute and laborious machinery of the second section [of the Royal Marriages Act]; that it should have interposed such checks against a marriage without [royal] consent, and at the same time have rendered such a marriage ultimately valid in one given set of circumstances, if the party himself who is the subject of such legislation, by an easy journey, or a voyage of a few hours, could render all these provisions useless, and set the statute at defiance by contracting a marriage abroad with whomever he thought proper.
He also noted that the Sovereign’s consent alone was sufficient to validate a marriage under the Act. The provisions about entering the consent onto the license and the register were directory and not essential. And although they agreed that the penal clause in the Act was defective, that didn’t invalidate its other provisions. Consequently, they held that d’Este hadn’t succeeded in making his claim.
Lord Lyndhurst consulted with the other members of the Committee and then proposed a resolution dismissing d’Este’s claim. In the ensuing debate, Lord Campbell observed that, even if the marriage was valid under the law of Rome, the plain words of the Royal Marriages Act was an insurmountable bar, and the other members expressed similar sentiments. The resolution dismissing d’Este’s claim was adopted, affirmed by the House, and then reported to the Queen.
D’Este died a few years later. Because he never had children, the peerages he claimed would likely have gone extinct anyway. The Sussex Peerage Case, on the other hand, would continue to shape the law for years to come, and it continues to be cited today. D’Este may have failed in his quest to become Duke of Sussex, but he nevertheless gained a place in the history books.
 The Prince described their courtship in a letter to Lord Erskine, quoted in John E. P. Wallis, ed., Reports of State Trials, vol. 6 (London: Her Majesty’s Stationery Office, 1894), 81 (hereafter cited as State Trials).
 The contract is printed in State Trials, 81-82.
 Section III of the Royal Marriages Act 1772.
 State Trials, 82.
 State Trials, 83.
 State Trials, 83.
 State Trials, 83.
 In her prayer book, Lady Augusta recorded that the marriage was conducted by “Rev. Mr.——.”
 State Trials, 83.
 Civil marriage did not exist yet.
 The Prince was twenty, and the age of majority at the time was twenty-one.
 This way, people could raise any objections to the wedding that they might have.
 Prince Augustus Frederick wasn’t the first of George III’s sons to defy the Royal Marriages Act. In 1785, the Prince of Wales secretly married Maria Fitzherbert. Because their marriage was invalid under British law, the Prince wasn’t disqualified from succeeding to the Throne under the Act of Settlement 1701 despite the fact that he’d married a Roman Catholic.
 An account of the Privy Council’s proceedings can be found in Horace Twiss, The Public and Private Life of Lord Chancellor Eldon, vol. 1 (London: John Murray, 1844), 234-235.
 The Attorney General, the future Lord Eldon, replied that it was a difficult business to bring a prosecution without forcing people to incriminate themselves.
 The King’s Proctor was one of the Crown’s Law Officers in the ecclesiastical courts.
 At that time, the ecclesiastical courts had exclusive jurisdiction over most matrimonial cases, though true divorce could only be obtained through a private Act of Parliament.
 Normally an appellate tribunal, the Arches Court could hear assume original jurisdiction if requested to do so by an inferior court.
 Unfortunately, the case does not appear to have been reported in full. However, a partial report can be found in Sir Robert Phillimore, The Ecclesiastical Law of the Church of England, vol. 1 (London: Henry Sweet, 1873), 749-750.
 The Duke’s wife was never recognized as Duchess of Sussex, but in 1840 Queen Victoria created her Duchess of Inverness in her own right.
 By longstanding custom, senior judges receive writs of assistance (also known as writs of attendance) obliging them to provide legal assistance to the House of Lords when necessary. Such writs are still issued today, though the judges’ attendance in Parliament is now confined to the State Opening.
 State Trials, 86.
 State Trials, 88.
 State Trials, 90-92.
 State Trials, 93.
 As Lord Campbell noted, “[b]y the Law of England, the declarations of deceased persons are generally not admissible unless they are against the pecuniary interest of the party making them.” State Trials, 97.
 The Roman Catholic hierarchy hadn’t yet been re-established in England in 1844.
 State Trials, 98.
 State Trials, 98-103.
 State Trials, 104.
 State Trials, 110.
 State Trials, 111-112.
 The most recent citation I could find comes from Scipion Active Trading Fund v Vallis Group Ltd  EWHC 1451.