During the early nineteenth century, the English East India Company (EIC) was in a state of transition in Penang, an island in the Straits of Malacca off the coast of the Malay Peninsula. Although the EIC had established strong ties with merchants based in Penang, they had failed to convince the EIC government in Bengal to invest them with more legal powers. As a result, they could not firmly extend formal jurisdiction over the region. The Anglo-Dutch Treaty (also known as the Treaty of London) that officially cemented EIC legal authority over the Straits of Malacca, was not signed until 1824, bringing the three Straits Settlements of Penang, Malacca, and Singapore under EIC rule officially in 1826. Prior to that, the EIC imposed their ideas of legitimacy on the region via other means, mainly through the co-optation of local individuals of all origins who were identified as politically and economically influential, by granting them EIC military protection, and ease of sailing under English flags. Because co-opted influential individuals could still be a threat to EIC authority in the region, EIC company officials eradicated competing loci of authority by discrediting them in courtroom trials in which they were treated as private individuals. All clients in EIC courts including royal personages in the region were treated like colonial subjects subject to English Common Law. By focusing on a series of trials involving a prominent merchant named Syed Hussain Aideed from 1816 to 1821, this article traces how EIC legal authority became pervasive at the eastern end of the Indian Ocean by the early nineteenth century without actual territorial conquest.