Not really, to be accurate. In fact, the Somerset case was barely even mentioned in the Americas IOTL, outside of a select few circles (probably because just about everybody knew that it only applied to Britain proper, apart from maybe a few paranoids who *might* have actually believed in a conspiracy.).
Well, that's not true.
"AUGUSTA, June 18, 1774. RUN away the 16th Instant, from the Subscriber, a Negro Man named BACCHUS, about 30 Years of Age, five Feet six or seven Inches high, strong and well made; had on, and took with him, two white Russia Drill Coats, one turned up with blue, the other quite plain and new, with white figured Metal Buttons, blue Plush Breeches, a fine Cloth Pompadour Waistcoat, two or three thin or Summer Jackets, sundry Pairs of white Thread Stockings, five or six white Shirts, two of them pretty fine, neat Shoes, Silver Buckles, a fine Hat cut and cocked in the Macaroni Figure, a double-milled Drab Great Coat, and sundry other Wearing Apparel. He formerly belonged to Doctor George Pitt, of Williamsburg, and I imagine is gone there under Pretence of my sending him upon Business, as I have frequently heretofore done; he is a cunning, artful, sensible Fellow, and very capable of forging a Tale to impose on the Unwary, is well acquainted with the lower Parts of the Country, having constantly rode with me for some Years past, and has been used to waiting from his Infancy. He was seen a few Days before he went off with a Purse of Dollars, and had just before changed a five Pound Bill; most, or all of which, I suppose he must have robbed me off [sic], which he might easily have done, I having trusted him much after what I thought had proved his Fidelity. He will probably endeavour to pass for a Freeman by the Name of John Christian, and attempt to get on Board
some Vessel bound for Great Britain, from the Knowledge he has of the late Determination of Somerset's Case. Whoever takes up the said Slave shall have 5 l. Reward, on his Delivery to GABRIEL JONES."
That's a notice that was published in the
Virginia Gazette of June 30 1774. Far from "a select few circles", Somersett was sufficiently well known that it was being blamed for slaves running away - which means that not only had masters heard of it, but slaves too.
And the real significance of Somersett in the colonies was down to the fact most colonial charters included wording to the effect that colonial law had to be consistent with English law, and the verdict in Somersett stated in the most forceful terms possible that slavery was not - it was a perfectly respectable opinion at the time that it was only a matter of time before the reach of Somersett extended to the colonies, not a wild conspiracy theory.
Hell, the fact that Thomas Jefferson himself attempted to introduce a few openly anti-slavery statements into the Declaration of Independence should tell you something right there
And the fact that he failed should tell you rather more. What the declaration eventually ended up doing was condemning the British for inciting "domestic insurrections amongst us," which, stripped of euphemism, is a condemnation of the practice of promising slaves their freedom if they enlist in the British army.
But the fact that Gerald Horne is so utterly wrong about the real world history is besides the point. What I'm asking about is, what kind of PODs we might need in order to make the scenario play out in an ATL.
It is basically OTL, all you really need more to fit the scenario in full is a bit more honesty and a bit less hypocrisy on the part of the rebels -
"If there be an object truly ridiculous in nature, it is an American patriot, signing resolutions of independency with the one hand, and with the other brandishing a whip over his affrighted slaves." Abolitionist Thomas Day, 1776.