Why did colonists oppose the Stamp Act?

American colonists protested the Stamp Act of 1765 because it was a tax imposed on them by the British Parliament instead of their elected colonial legislatures. They believed it was unjust to be taxed without their consent by unelected rulers.

The Stamp Act was opposed by the colonists because it represented an effort by the British to use taxes in order to raise money, and not to adjust change in the past.