common law 
noun
1 [mass noun] The part of English law that is derived from custom and judicial precedent rather than statutes. Compare with case law, statute law.Another is the common law, derived from precedent and judges' interpretations of the law....
- Equity awarded simple interest at a time when courts of law had no right under common law or statute to award any interest.
- Generally, the system of law in use worldwide can be classified into common law and statute law.
1.1The body of English law as adopted and adapted by the different States of the US. Compare with civil law.Under the U.S. system, the judiciary is charged with ensuring that the principles embedded in the Constitution, statutes, and common law are honored regardless of what the majority thinks....
- The ruling is based on the federal Lanham Act, which prohibits false and deceptive advertising, and Missouri common law dealing with unfair competition.
- Prior to 1970, many states, by statute or common law, dictated that fathers had a right to have their children bear their surnames.
2 [as modifier] Denoting a partner in a marriage recognized in some jurisdictions (excluding the UK) as valid by common law, though not brought about by a civil or ecclesiastical ceremony: a common-law husband...
- Her mother stood next to an open doorway and sobbed yesterday as the undertakers brought down her common-law husband's body.
- Pension providers were recently asked if they make a point of never providing pensions for common-law partners under any circumstances.
- The policy permits Iowa State to offer the same insurance credits for domestic partners enrolled in an Iowa State benefits plan as it does for married or common-law partners.
2.1Denoting a partner in a relationship in which a man and woman cohabit for a period long enough to suggest stability.There is always a feeling of insecurity by the female partner in any common-law relationship....
- During their 20-year common-law relationship, they lived in Calgary, Portage La Prairie and Ottawa.
- When a woman in a common-law relationship has a child, her male partner is automatically considered the father, unless she enters another name on the birth certificate.