Joseph Knight (slave)

When the justices of the peace found in favour of Wedderburn, Knight appealed to the Sheriff of Perth, John Swinton. He found that "the state of slavery is not recognised by the laws of this kingdom, and is inconsistent with the principles thereof: That the regulations in Jamaica, concerning slaves, do not extend to this kingdom."[2][3] The defence of Knight was mounted in general terms as a denunciation of slavery:[4]

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, whether he was ensnared, or bought from his parents, the iniquity is the same. - That a state of slavery has been admitted of in many nations, does not render it less unjust. Child-murder, and other crimes of a deep dye, have been authorised by the laws of different states. Tyranny, and all sorts of oppression, might be vindicated on the same grounds. - Neither can the advantages procured to this country, by the slavery of the negroes, be hearkened to, as any argument in this question, as to the justice of it. Oppression and iniquity are not palliated by the gain and advantage acquired to the authors of them. 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 in turn appealed to the Court of Session in Edinburgh, Scotland's supreme civil court, arguing that Knight still owed perpetual service, in the same manner as an indentured servant or an apprenticed artisan. The case was considered important enough to be given a full panel of judges, including Lord Kames, a prominent legal and social historian.

Henry Dundas, then Lord Advocate, acted as Knight's counsel and was assisted in his preparation for the case by James Boswell and Samuel Johnson. "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."[5] Their argument was that 'no man is by nature the property of another'. Dundas submitted that since there was no proof that Knight had given up his natural freedom, he should be set free. Conversely, Wedderburn's counsel argued that commercial interests, which underpinned Scotland's prosperity, should prevail. Dundas concluded his remarks by stating: “‪Human nature, my Lords, spurns at the thought of slavery among any part of our species.”‬

In an unexpected decision, Lord Kames stated that 'we sit here to enforce right not to enforce wrong' and the court emphatically rejected Wedderburn's appeal. It ruled that

‘the dominion assumed over this Negro, under the law of Jamaica, being unjust, could not be supported in this country to any extent: That, therefore, the defender had no right to the Negro’s service for any space of time, nor to send him out of the country against his consent: That the Negro was likewise protected under the act 1701, c.6. from being sent out of the country against his consent.’[2]

In effect, slavery was not recognised by Scots law. 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.[6]