The Declaration of Independence that was signed on July 4th, 1776 did not represent the culimination of a practical policy decision to separate from Britain. It was a response--an angry, desperate response--to British oppression of North American colonists. Here are ten specific British policies to which the signers of the Declaration of Independence were responding.
1. Taxation Without RepresentationTo fund its military projects, and to assert its control over an increasingly independent group of colonies, Britain began to enforce painfully high taxes and tariffs on such goods as molasses, paper, sugar, and tea. With no representation in Parliament, American colonists who felt the taxes to be excessive had no recourse other than civil disobedience.
2. No Free TradeDuring the 18th century, Britain was an empire in competition, sometimes militarily and sometimes economically, with other empires. In order to prevent other nations from benefitting from the North American colonial market, Britain brought its navy to bear against U.S. attempts to purchase non-British goods. Given the prohibitively high trade tarrifs enforced by Britain (see below), this policy was for all practical purposes unenforceable.
3. Unlimited Search and SeizureTo discourage smuggling, the British government awarded Writs of Assistance to British officers in the colonies. The Writs gave officers the power to search any residence or building, without warning or supervision, and to confiscate whatever they deemed to be smuggled or otherwise improperly obtained goods. This widely abused policy would ultimately inspire the Fourth Amendment to the U.S. Constitution.
4. Destruction of Colonial GovernmentThe governments of the colonies, unrepresented in the British system and remote from the imperial legislative process, began to create their own elected bodies. The British government did not care for this idea, and took extra measures to see to it that local elected colonial government did not achieve autonomy, even with respect to matters that did not directly affect the larger British Empire.
5. Oppression of Political ProtestersAs colonial protest against British government became more common, British colonial law enforcement authorities took measures to crack down on dissent. Among the more infamous examples of this were the 1769 imprisonment of Alexander McDougall (on "libel" charges) for his work To the Betrayed Inhabitants of the City and Colony of New York, and the 1770 Boston Massacre in which British troops fired on a crowd of colonial protesters, killing five.
6. Immunity for Corrupt and Abusive British OfficersThe Boston Massacre trial was an interesting spectacle. Eight British soldiers were accused, but defended by the future president John Adams, who won acquittal for six of the eight and the equivalent to a dishonorable discharge for the other two. Still, British leaders were concerned enough to pass a law mandating that any British officers accused of an offense be tried in England (where witnesses would be hard to find) rather than in the colonies.
7. Direct Control of the Criminal Justice SystemOver a period of decades, as distrust of colonial authorities grew, the British government began to deny jury trials and place both verdicts and punishments in the hands of judges. As time wore on, the British government also took measures to ensure that those judges would be selected, paid, and supervised by British rather than colonial authorities.
8. Guilty by ParliamentCentralized British control of the criminal justice system, with no possibility of trial by jury, may seem to suggest that colonists were at the mercy of British officers--but the truth is that they always had been. By sheer fiat (through resolutions called Bills of Attainder), Parliament could declare any person to be "tainted," imprisoning or even executing the subject and confiscating all of his/her property without trial.
9. Forced Quartering of SoldiersFrom the beginning, colonies were held responsible for hosting facilities to house British soldiers. But as colonial dissent began to grow, the British government mandated a new and far more distressing requirement: Individual colonists would be required to let British soldiers live in their private homes. In the wake of the Boston Massacre, and given the particular sense of conflict in the pre-Revolutionary years, this was as traumatic as it was inconvenient.
10. Closure of the Boston PortColonial and British tensions came to a head when sixty colonists, dressed up as American Indians, protested high tariffs and the British monopoly on imported goods by dumping 342 crates of tea delivered by the British East India Company into the Atlantic Ocean. The event, referred to as the Boston Tea Party, provoked Parliament to pass a law closing the Boston port until the colonies managed to gather up enough money to pay for the tea. To this day, the tea debt has not been paid.