A more thorough explanation:

Definition: Lord Lyndhurst's Act, also known as the Marriage Act of 1835, was an English statute that declared marriages within certain degrees of kinship to be null and void.

Example: If a brother and sister were to get married, their marriage would be considered null and void under Lord Lyndhurst's Act.

This act was put in place to prevent marriages between close relatives, which were seen as morally and genetically problematic. The example illustrates how the act would apply in a specific scenario, where a brother and sister attempt to marry.