History tells us that the law has played both a negative and a positive role in the progress of black people's rights. During Black History Month we look at an important case, which initiated the end of the UK's slave trade.

The British Transatlantic Slave Trade ship, the Zong, left port in Accra, Ghana on 18 August 1781 bound for Jamaica. Aboard were 442 enslaved African people - twice the number of people it could safely transport.

In Jamaica's waters, the crew made a critical navigational error, mistaking Jamaica for the French colony Saint-Domingue. On 29 November and over the days that followed, the crew forced over 130 enslaved people overboard to their deaths. The crew claimed that they had been thrown overboard because the ship did not have enough water to keep everyone alive for the rest of the voyage – a claim later proven false.

If the enslaved people had died onshore, the ship-owners would have no redress from their insurers. Similarly, if they died a 'natural death' at sea, the insurance could not be claimed. If some were thrown overboard in order to save the rest of the 'cargo' or the ship, then a claim could be made under 'general average' (This principle holds that a captain who jettisons part of his cargo in order to save the rest can claim for the loss from his insurers.) The ship's insurance covered the loss of enslaved people at £30 per person.

The Zong arrived at its destination on 22 December where the remaining enslaved people were sold at an average price of £36 per person.

On its return to Britain, the owners of the ship commenced an action at the Guildhall in London claiming for the loss of the enslaved African people, described as 'lost cargo.' This was initially granted by the court (following a jury trial overseen by the Lord Chief Justice) and £3,660.00 was awarded to the ship owners.

An appeal was pursued by the insurers at the Court of the King's Bench in Westminster Hall. New evidence was heard, that despite heavy rain having fallen on the ship on the second day of the killings, a third group of enslaved people was still killed after that. It was concluded that the insurers were not liable for losses resulting from the errors committed by Zong's crew and another trial was ordered by the court. There is no evidence that another trial was held on the issue and unbelievably, no member of the crew was ever prosecuted for murder.

The Zong massacre did eventually gain both national and international attention. Granville Sharp (an anti-slave trade activist) campaigned to raise awareness of the Zong massacre, writing letters to newspapers, the Lord Commissioners of Admiralty and the Prime Minister. Bishops and quakers critical of the slave trade began to campaign against slavery, with their petition based on the Zong massacre being one of the first submitted to Parliament.

In 1788 Parliament enacted the Slave Trade Act, which was the first piece of legislation to regulate the slave trade, leading to the Slave Trade Act of 1807 which prohibited the Atlantic slave trade. The United States also prohibited the Atlantic slave trade in 1808. The slave trade was eventually abolished in most British colonies with the enactment of the Slavery Abolition Act 1833 and the League of Nations 1926 Slavery Convention sought global prohibition of slavery and the slave trade.

Anti-slavery legislation is still being updated in modern day law; the UK Parliament introduced the Modern Slavery Act in 2015, which brought together previous laws seeking to prevent and prosecute slavery, servitude, forced labour and human trafficking, as well as making businesses (over a certain size) accountable for slavery and labour abuses in their supply chain. In Scotland, the Human Trafficking and Exploitation Act (Scotland) 2015 clarified, strengthened and brought together existing laws on human trafficking.