This line of the declaration of independence refers to the quartering act of 1774, which was enacted by parliament in response to

The Quartering Act of 1774 was part of the Intolerable Acts, which were enacted by Parliament in response to the Boston Tea Party.

Explanation:

On December 16, 1773 took place in Boston, Massachusetts, the Boston Tea Party, in which a whole shipment of tea was launched into the sea. A group of settlers disguised as Indians threw the tea load of three British ships into the sea. It was an act of protest by the American settlers against Britain and is considered a precedent of the United States War of Independence.

As a result of these events, on June 2, 1774, the Parliament voted a group of laws including a new Quartering Act. This law is one of the Intolerable Acts, the purpose of which was to secure British jurisdiction over the Thirteen Colonies of North America. The new Quartering Act extended the previous legislation, as it was expected that the troops will not only be housed in commercial or empty buildings but also in inhabited houses. The law would be hotly contested, symbolizing for the settlers the potential dangers and abuses that could be expected from a troop of occupation.