A quick definition of in quantum locupletiores facti sumus ex damno alterius:

Term: IN QUANTUM LOCUPLETIORES FACTI SUMUS EX DAMNO ALTERIUS

Definition: This is a Latin phrase from Roman law that means if we have gained something because someone else lost something, we are responsible for giving it back. It refers to a rule that says if someone manages or interferes in another person's business without permission but out of kindness or friendship, they must finish the job and give the profits to the owner. The person who interfered can be reimbursed for any expenses they had, but they cannot keep any of the profits for themselves. This rule only applies if the person who interfered did it out of kindness and not for their own benefit, and if the owner did not tell them to do it.