Thomas Jefferson is the one most responsible for writing the Declaration of Independence.
The king refused to assent to laws that were wholesome and necessary for the public good.
The king had forbidden colonial governors to enact laws or implement laws without his assent (which, as the prior point noted, he was in no hurry to give).
The king forced people to give up their rights to legislative assembly or forced legislative bodies to meet in difficult places that imposed hardships on them.
The king dissolved legislative assemblies and then refused for a long time to have other assemblies elected.
The king obstructed justice in the colonies and made judges dependent on his will alone for their salaries and their tenure in office.
The king kept standing armies in place in the colonies in peacetime, without the consent of the colonial legislatures.
The king imposed taxes without the colonists' consent.
There were more items listed by Jefferson, but you get the idea. He was justifying revolution by proving tyranny was standard operating procedure by the British monarchy.
