A more thorough explanation:

Vadiare legem is a Latin term used in law which means "to wage law". It refers to the practice of a defendant in a debt action giving security to make one's law on a day assigned. This means that the defendant would pledge, upon giving the security, to do two things on the appointed day in court:

1. Take an oath in open court that the debt was not owed.
2. Bring 11 compurgators who would swear that they believed what the defendant said.

For example, if someone owed money to another person and the creditor took them to court, the debtor could vadiare legem. This meant that they would give security to the court and then appear on a specific day to take an oath and bring 11 people who would swear that they believed the debtor did not owe the money.

This practice was common in medieval England and was used as a way for defendants to avoid paying debts that they claimed were not owed. However, it was eventually abolished in the 19th century.