This law is seen in Brazilian historiography as a British retaliation against the Alves Branco Tariff, a tariff reform established in 1844 by Finance Minister Manuel Alves Branco that raised import duties[1][2] followed by the ending of the British-Brazilian Convention of 1826 on the Atlantic slave trade to Brazil.

Over the following years, the number of cases in British admiralty courts increased dramatically due to the large number of Brazilians arrested for slave-trading – in the first six months of 1848, 19 out of 33 cases heard by the vice admiralty court in St. Helena were Brazilian.

In September 1850, new legislation outlawing the slave trade was enacted, and the Brazilian government began to enforce it.

[3] On 27 April 1852, the British government notified its counterpart in Brazil of its permanent withdrawal of warships from Brazilian waters, on condition that there be no resumption of the slave trade; the reports of the British minister to Brazil in 1860 and the following year, showed no indication of breach.

Finally satisfied there would be no resumption of the African slave trade, the British parliament repealed the Aberdeen Act on 19 April 1869.