Common-law marriage, also known as sui iuris marriage, informal marriage, marriage by habit and repute, or marriage in fact, is a legal framework in a limited number of jurisdictions where a couple is legally considered married, without that couple having formally registered their relation as a civil or religious marriage. Common-law marriage, also known as sui iuris marriage, informal marriage, marriage by habit and repute, or marriage in fact, is a legal framework in a limited number of jurisdictions where a couple is legally considered married, without that couple having formally registered their relation as a civil or religious marriage.