Serving as an advisor to King Rama V of Thailand, he played a crucial role in the reformation of that country to modern western standards and was awarded the title Chow Phya Abhai Raja, the highest distinction ever granted to a foreigner.

His father had graduated with distinction from the University of Leuven (French: Louvain), after which he was sworn in as solicitor and travelled to Berlin where he followed classes by von Savigny and Hegel.

He was in an excellent position to contact many experts in the field, and consultations led to the founding of the Institut de Droit International in the townhall of Ghent on 8 September 1873.

According to this view, the free interchange of goods and services and personal freedom should not be restricted by interventions of the state, even though this principle was relaxed somewhat in times of crisis.

On the Roman Catholic side, the ultramontanists became the dominant faction, partly under influence of the papal Encyclical Quanta cura (1864) and especially the attached Syllabus Errorum in which the modern liberties were sharply condemned.

On the liberal side, mostly in circles of freemasons and the Université Libre de Bruxelles, the principle of "Free Research" (Vrij Onderzoek) gained influence, which, as it was interpreted there and then, was incompatible with catholic orthodoxy.

In order to achieve this aim, they were forced to interventions of the state, since social life was completely dominated by Roman Catholic organisations.

The main battleground, however, was the field of education and the academic freedom of Belgian universities, where rationalism and scientific positivism were gaining ground.

The situation came to a head with the affair Laurent-Brasseur, two professors from Ghent who had, in the view of the clergy, made ex cathedra statements contradicting the official teachings of the Church.

This affair brought to light the deep divisions between liberals and Catholics and the country was divided into two camps: a clerical one and an anti-clerical one who battled each other in every way possible.

After the liberal victory in the elections of 1878, Rolin-Jaequemyns accepted the post of Minister for the Interior in the cabinet of the "papenvreter" ("catholic-muncher") Walthère Frère-Orban who unleashed the "School Struggle" (Schoolstrijd).

Catholic schools sprang up everywhere and a battle, fought with a fanaticism that would reverberate through Belgian society for decades to come, raged for every teacher and every pupil.

Rolin-Jaequemyns, who had played a major role in this cabinet, was excommunicated with the rest of the cabinet-members, though this was later revoked due to the intervention of his brother Edouard.

He applauded the founding of the Association Internationale Africain in 1876 by King Leopold II and especially its scientific and philanthropic goals, even though its main mission was strictly colonial.

Four years later Rolin-Jaequemyns was appointed member of the Conseil Supérieur for the Congo Free State, which had been created by Leopold II as a reaction to the rising criticism of the Belgian conduct.

On the other hand, he did not try to defend Leopold's colonial politics, as other Belgian jurists, such as Félicien Cattier, Ernest Nys, and Edouard Descamps, had done.

During a lunch hosted by the British ambassador in December 1891, he met Prince Damrong of Siam, who had gone to Europe to search for a General Advisor for his half-brother King Chulalongkorn (Rama V).

The third condition enormously complicated administration of the country as many people claimed ties to colonies elsewhere as a means to escape justice or avoid corvee labour obligations.

[3] Rolin-Jaequemyns wrote that he was "convinced that this is a systematic campaign undertaken by colonial authorities of Annam and Cambodia destined to veil the little success as well as to justify the enormous costs of their interior administration."

In 1906, Siam ceded Battambang and Siem Reap in Cambodian territory to French Indochina; and in the Anglo-Siamese Treaty of 1909, relinquished claims to Kedah, Kelantan, Perlis, and Terengganu in Upper Malaya.

King Chulalongkorn understood that his kingdom could survive only by modernizing its judicial, administrative and military capacity and thus offer the colonial powers sufficient incentives and deterrents to respect its sovereignty.

In 1895, he wrote to the president of the International Association for Comparative Legal Studies that the material proved highly interesting and was an indispensable preparation for the reform.

Instead one should strive to preserve the traits of the traditional law, (which in the case of Siam was based on the Dharmasastra, a buddhist system) while bringing them up-to-date with modern requirements.

With the help of expatriate advisers and the support of European-educated princes, the King managed to separate his personal fortune from the state treasury and create a bureaucracy to replace a government structure which had its roots in the 15th century.