User blog comment:Tholanar/If you were the High Queen or King of Skyrim..../@comment-4057437-20121220094550/@comment-5135631-20121223105801

From the Skyrim loading screen:

"Each of Skyrim's nine holds is ruled by a Jarl. The Jarls are largely independent, but each swear fealty to Skyrim's High King."

Frome that it seems clear that the High King is still above the Jarls and have more power. Also, the High King is one of the Jarls, and thus normally the most powerful Jarl. The only contradiction we know of this is 4E201, where Ulfric Stormcloak was the most powerful Jarl but not High King.

Also, in England, it varied by King. King John was weak, so that's one of the reasons why the magna carta got past him, but if they tried something like the Magna Carta on Henry VII he would have eaten their souls. Kings before the Norman Conquest were normally respective of the Earls (English equivalent of Jarls) anyway, and the Witan, which was kind of like the Moot. King Henry VI was weak and faced civil war for decade which he eventually lost, but his successor Edward IV was very powerful.