The law that resulted in violence and property destruction, leading to the closing of Boston Harbor, was the Tea Act of 1773. The Tea Act granted the British East India Company a monopoly on tea sales in the American colonies, allowing them to sell tea at a price lower than that of colonial merchants. This angered many colonists, who saw it as an attempt to reinforce British control and undermine local commerce.
In response to the Tea Act, colonists organized the Boston Tea Party on December 16, 1773, where they protested by boarding British ships and dumping hundreds of chests of tea into Boston Harbor. In retaliation for the Boston Tea Party and other acts of defiance, the British Parliament passed the Coercive Acts (also known as the Intolerable Acts) in 1774, which included measures such as closing Boston Harbor until the dumped tea was paid for, further escalating tensions between the colonies and Britain.