The Molasses Act was a British law of 1733 imposing a prohibitive duty of six pence a gallon on rum and five shillings a hundredweight on sugar imported from the foreign colonies of the West Indies into the English colonies of America. Since the colonies needed exports to offset their adverse trade balance with the mother country, they developed the so-called "Triangle Trade," which in its simplest form involved the purchase of rum (or sugar which could be converted into rum) from the West Indies, combined with the export of rum and trinkets to Africa in return for African slaves that could then be sold in the West Indies.
The planters of the British West Indies protested against the trade with the foreign islands, and demanded protection from this competition. Parliament thereupon passed the Molasses Act over the protests of the trading colonies.
The effects of the act were minimized through widespread smuggling. The American colonists justified their action on the grounds that compliance with the act would have ruined their economy. The Molasses Act was repealed by the Sugar Act of 1764.