House law or House laws ("Hausgesetze") are rules that govern a royal family or dynasty in matters of eligibility for succession to a throne, membership in a dynasty, exercise of a regency, or entitlement to dynastic rank, titles and styles. Prevalent in European monarchies during the nineteenth century, few countries have house laws any longer, so that they are, as a category of law, of more historical than current significance. If applied today, house laws are mostly upheld by members of royal and princely families as a matter of tradition.