When James I died in 1437, his son King James II was crowned when only 6. Sir Alexander Livingston had by this time risen to become Lord High Treasurer and advisor to the young king. At this time, they had little influence over other baronial families who wielded power over their estates. The Black Douglas family was the most powerful in Scotland; the 5th Earl of Douglas was the heir to the throne provided James II died without issue. The 5th Earl was to die first, though, in 1439.
The regent Sir William Crichton and Livingston invited the 6th Earl, fourteen year old William Douglas and his party to Edinburgh Castle to dine with the king in 1440. A head of a black bull was served - meaning death. The Douglas party were hurriedly tried and executed. William's great-uncle, James the Gross, became the 7th Earl of Douglas. He was believed by some to have been part of the conspiracy to murder his great-nephew. In 1443, he was succeeded by his son William, the 8th Earl.
The Black Douglas family clawed back its power. The young Earl was making allies with the English, the 'Tiger Earl' Crawford, and John of the Isles - all highly dangerous for the crown. On the pretext that the Livingstons had embezzled funds from the Treasury, the 8th Earl of Douglas had Robert Livingston of Drumry and the Lord High Treasurer's son, Sir Alexander of Phildes, executed (hanged and then beheaded) at Castle Hill, Edinburgh in January 1450. The elderly Lord High Treasurer was imprisoned in Dumbarton Castle.
Whether or not the embezzlement was true, there was another reason for this purge of the Livingstons. Part of the Livingston estate was to be part of the marriage portion of James II new wife, Mary of Gueldres, married on 3rd July 1449. The day after the Livingstons' execution, Parliament confirmed the marriage portion. It seems probable that the Douglases were behind the rise of the Livingstons and when the family got too powerful for their liking were also behind their fall.
James II had the Earl of Douglas killed at Stirling Castle in 1452. He dealt with the Douglas-led backlash by using heavy cannon against their estates. He took the 9th Earl, James, prisoner and raised a charge of treason against the family, forfeiting their estates around 1455. James II died in 1460 trying to recover Roxburgh Castle from the English when one of his own cannons exploded.