From an initial review of the materials, it can be concluded that the ‘Hukum Kanun’ (Legal Code) Brunei had the characteristics of the syariah. This was because Brunei rulers professed the Islamic faith since the time of Sultan Muhammad Shah, aka Alak Betatar, who became a Muslim in the early 1360s.
As far as the constitution, written or unwritten, is concerned, it was unclear the extent to which it had adhered to the principles of the Medinah Charter promulgated by Prophet Muhammad (PBUH). The 44 or more chapters of the Brunei Legal Code were short on the structure of a nation state, rules of governance and administration which had to be based on the syariah.
For example, a successful nation state require loyalty, patriotism from its plural citizenry, a requirement approved by Islam, as revealed in the Quranic verse:
“O people, We created you from the same male and female and rendered you into distinct peoples and tribes that you may recognize one another. The best of you in the sight of God is the most righteous.” (Sūrat al-Ḥujurāt, 49:13)
There was no specific mention in the then Brunei Legal Code relating to this provision. Whether it was in the ‘unwritten constitution’ was also unclear. However, it could be inferred, from past and current practices, that loyalty and patriotism are required of Brunei’s citizenry. These included the ‘titah’ of His Majesty on numerous occasions, statements of the ministers and actions taken against those deemed disloyal and a threat to national security.