Who enforced anti-slave trade laws by sending warships to intercept slave ships?

Great Britain, during the early 19th century, enacted strong anti slavery laws and enforced them in their role as the world's superpower. This came about during the early Victorian era as morality became a key issue in government a public revulsion towards the construct of slavery became common. Military intervention was taken against the muslim countries of North Africa who were the main perveyors of the slave trade. Naval intervention in the Atlantic also served to reduce the flow of slaves to the US and and also served to influence public opinion in the US against slavery, eventually becoming a factor in the US civil war of 1861-1865 and the emancipation of existing slaves and the outlawing of the institution of slavery.

Acase involving the laws of a single state.