How did the colonists justify their protests and ultimate rebellion ?

The Crown was using the colonies as an economic tool, so they imposed rough taxes without consent, and restricted its trading partners so Britain can make a huge profit. People in the colonies thought these measures (and others, such as quartering troopsand suspending local legislatures) were a huge violation of their rights [as British subjects], particularly because they weren't represented in Parliament.

Source:Hours of study in AP US History