1788 - The Slave Trade Act 1788, also known as Dolben's Act

A British Act of Parliament that placed limitations of the number of people that British slave ships could transport, related to tonnage. It was the first British legislation passed to regulate slave shipping.

In the late 18th century, opposition to slavery was increasing. Many abolitionists were aroused by the Zong massacre, whose details became known during litigation in 1783, when the syndicate owning the ship filed for insurance claims to cover 132-142 slaves who had been killed. Quakers had been active in petitioning Parliament to end the trade.


Slavers Throwing overboard the Dead and Dying—Typhoon coming on, painting by J.M.W. Turner

To expand their influence, in 1787 they formed a non-denominational group, the Society for the Abolition of the Slave Trade, which included Anglicans of the established church (non-Anglicans were excluded from Parliament).

In 1788, Sir William Dolben, led a group of his fellow Members of Parliament to the River Thames to board and examine a ship being fitted for a slaving voyage. Dolben had been in contact with the Abolition Society in the previous year. His visit to the slave-ship appears to have hardened his opposition to the slave trade.

The Society's campaigning led the Prime Minister, William Pitt, to order an investigation into the slave trade. He also asked William Wilberforce to begin a debate in the House of Commons on the issue. However, by May 1788, the trade committee of the Privy Council—which Pitt had tasked with investigating the slave trade—had not produced its report.

On 9 May 1788, Pitt introduced a motion to the House of Commons which asked whether parliament should delay its consideration of the slave trade until its next session. He argued that the great number of anti-slavery petitions that had been presented to the House on this topic meant that a proper consideration of the issue could not occur with so little time left in the current parliamentary session. Representatives from Liverpool, a city whose merchants controlled much of the British slave trade and whose economy was deeply tied to it, welcomed Pitt's motion. They argued for a debate to enable them to refute the accusations about the slave trade made in the petitions submitted to the House.

Sir William Dolben, representing Oxford University, eventually rose to speak. He argued that 10,000 lives would be lost if the House did not immediately intervene to curtail the abuses perpetrated during the Middle Passage. He said that immediate measures should be introduced to restrict the number of Africans that slave ship captains could take on board, as a means to reduce losses. This would reduce mortality due to the diseases of overcrowding and poor sanitation. Although Dolben opposed the slave trade, he did not at this time propose abolishing it or the institution of slavery.

Dolben's speech was disputed by Lord Penrhyn, one of the two MPs for Liverpool. He claimed that captains were highly motivated to preserve the lives of as many slaves as possible, so that they could profit from their sale.

Encouraged by Pitt, Dolben drafted a bill and submitted it to the House on 21 May. The bill passed its second reading on 17 June, and its third reading the following day. It was sent to the House of Lords, where it was approved in its first, second, and third readings, the last of which occurred on 2 July. However, because the Lords had amended the bill—adding a compensation clause, which the Commons felt infringed its right to deal exclusively with money matters—a new bill was drafted, passed, and resubmitted to the Lords. This was passed by them on 10 July, and received royal assent soon after. It was the first British legislation to regulate slave ships.

The Brookes was a British slave ship of the 18th century that became infamous after prints of her were published in 1788.

An engraving first published in Plymouth in 1788 by the Plymouth chapter of the Society for Effecting the Abolition of the Slave Trade depicted the conditions on board the Brookes and has become an iconic image of the inhumanity of the slave trade.

The image portrayed slaves arranged on the ship's lower deck and poop deck, in accordance with the Regulated Slave Trade Act of 1788.[2] The Brookes was reportedly allowed to stow 454 African slaves, by allowing a space of 6 feet (1.8 m) by 1 foot 4 inches (0.41 m) to each man; 5 feet 10 inches (1.78 m) by 1 foot 4 inches (0.41 m) to each woman, and 5 feet (1.5 m) by 1 foot 2 inches (0.36 m) to each child. However, the poster's text alleges that a slave trader confessed that before the Act, the Brookes had carried as many as 609 slaves at one time.

Other records indicate several other problems with the image. 1) The image portrays 487 slaves while on the voyage prior to when the measurements were taken the ship held 638 persons, the next journey 744, and the journey following the measurements, 609. 2) The planking as depicted on the outside of the ship is disproportionately too thick. 3) Stowage of slaves on multiple layers of decks does not allow for the storage of water and provisions, which was the common practice. 4) No deck hatches are illustrated, only small ladders. There would be no way for the ship to load and unload provisions, especially for the legs of the voyages with no slaves aboard. Despite these flaws this image has become the one most used to depict conditions on a slave ship over that of many other more accurate images.

Other physical objects that also were part of slave ships are not depicted. Slave ships had security features to keep the crew safe from their human cargo, such as barricade or wall to separate them while outside; nets alongside the ship to prevent slaves from jumping overboard; and armaments to keep the ship from being taken by other ships, such as swivel guns. Below deck bulkheads to separate women and children from men should be shown. Below deck, portholes were common to allow more ventilation, while outside of the ship sails positioned alongside funneled air below. These special sails made it easy to identify a slave ship at sea. Above deck, there would be a large cook stove to create the slave meals of commonly rice and beans.

The Slave Trade Act 1788 was supported by some abolitionists, including Olaudah Equiano, an African who was a former slave. But, some abolitionists, such as William Wilberforce, feared that the act would establish the idea that the slave trade was not fundamentally unjust, but merely an activity that needed further regulation.

The mortality of slaves on British ships declined during the 1790s. This act helped to lower the overall mortality rate of British ships during the 1790-1830 time period. Due to the lower density of slaves, illnesses could be controlled and food rations would last longer. During this period, ship captains were also given incentives for lower mortality rates. As their incentives would grow, their mortality rates would continue to lower. This information could have been manipulated by greedy captains but the research shows a general downward trend.

The historian Roger Anstey has suggested that this decline might be explained by the restrictions of Dolben Act. But, the research of several other historians has suggested that there is no demonstrable relationship between reduced crowding and lower mortality rates amongst slaves.[20] More recent research suggests that early work was plagued with measurement error due to bad record keeping), and this act did reduce crowding-related mortality. Slave mortality on Dutch ships, which were not subject to restrictions on the number of slaves carried, did not decline during the same period.