Inspired by Somersett's Case (1772), in which the courts had held that slavery did not exist under English common law, Knight resisted his claim.
Wedderburn appears to have been indignant, feeling that he had bestowed considerable gifts on Knight by educating him and taking care of him, and had him arrested.
[1] When the justices of the peace found in favour of Wedderburn, Knight appealed to the Sheriff of Perth, John Swinton.
"[1][2] The defence of Knight in the Court of Session was mounted in general terms as a denunciation of slavery:[3] The means by which those who carried this child from his own country got him into their hands, cannot be known; because the law of Jamaica makes no inquiry into that circumstance.
But the expediency of the institution, even for the subjects of Great Britain, is much doubted of by those who are best acquainted with the state of the colonies; and some enlightened men of modern times have thought, that sugar and tobacco might be cultivated without the slavery of negroes.In 1777 Wedderburn appealed to the Court of Session in Edinburgh, Scotland's supreme civil court, arguing that Knight still owed him perpetual service and might be taken and sent back to Jamaica by force.
The case came before the whole court of twelve judges (as was usual at that time) including Lord Kames, a prominent legal and social historian.
"I cannot too highly praise the speech which Mr. Henry Dundas generously contributed to the cause of the sooty stranger", Boswell recalled, "I do declare that upon this memorable question he impressed me.
Lord Auchinleck, Boswell's father, said "Although, in the plantations, they have laid hold of the poor blacks, and made slaves of them, yet I do not think that that is agreeable to humanity, not to say to the Christian religion.
Fugitive slaves (or 'perpetual servants') could be protected by the courts, if they wished to leave domestic service or were resisting attempts to return them to slavery in the colonies.