How would you describe "common law"?

. It is a law that is not written into the statutes, but is commonly recognized as law. Common law marriages are one example. In some states when a couple cohabitates for a certain number of years, they are considered married by common law, even though they have not had a civil ceremony or religious ceremony

"A "common law system" is a legal system that gives great precedential weight to common law, so that consistent principles applied to similar facts yield similar outcomes. The body of past common law binds judges that make future decisions, just as any other law does, to ensure consistent treatment. In cases where the parties disagree on what the law is, a common law court looks to past precedential decisions of relevant courts. If a similar dispute has been resolved in the past, the court is usually bound to follow the reasoning used in the prior decision (this principle is known as stare decisis). If, however, the court finds that the current dispute is fundamentally distinct from all previous cases (called a "matter of first impression"), judges have the authority and duty to make law by creating precedent. Thereafter, the new decision becomes precedent, and will bind future courts.

In practice, common law systems are considerably more complicated than the simplified system described above. The decisions of a court are binding only in a particular jurisdiction, and even within a given jurisdiction, some courts have more power than others. For example, in most jurisdictions, decisions by appellate courts are binding on lower courts in the same jurisdiction, and on future decisions of the same appellate court, but decisions of lower courts are only non-binding persuasive authority. Interactions between common law, constitutional law, statutory law and regulatory law also give rise to considerable complexity. However, stare decisis, the principle that cases should be decided according to consistent principled rules so that similar facts will yield similar results, lies at the heart of all common law systems."

Thanks for the invite,

 Unfortunately I'm not expert in the field and I will leave the answer for an expert. Yes, I have an idea about that, but I can not give an expert's answer.

Law protects everyone

Regulates the relations between everyone

Defines the duties

Punishes the guilty even be a lesson

One of the two major legal systems of the modern Western world (the other is civil law), it originated in the UK and is now followed in most English speaking countries. Initially, common law was founded on common sense as reflected in the social customs.

1. Common Law: The ancient law of England based upon societal customs and recognized and enforced by the judgments and decrees of the courts.

2. Common Law: Islamic Law is a common law. Born in the Middle Ages, it is seen in varying degrees-most forcefully in Saudi Arabia or Iran, moderately in Egypt, and hardly in Morocco. Its primary source is the Quran, the celestial and eternal book dictated by Allah to his Prophet Muhammad (PBUH) through the Angel Gabriel.

1. the part of English law that is derived from custom and judicial precedent rather than statutes.     
   • • the body of English law as adopted and modified separately by the different states of the US and by the federal government.
    
   • • denoting a partner in a marriage by common law (which recognized unions created by mutual agreement and public behavior), not by a civil or ecclesiastical ceremony.
    
   • • denoting a partner in a long-term relationship of cohabitation.
    

One of the two major legal systems of the modern Western world (the other is civil law), it originated in the UK and is now followed in most English speaking countries. Initially, common law was founded on common sense as reflected in the social customs. Over the centuries, it was supplanted by statute law (rules enacted by a legislative body such as a Parliament) and clarified by the judgments of the higher courts (that set a precedent for all courts to follow in similar cases). These precedents are recognized, affirmed, and enforced by subsequent court decisions, thus continually expanding the common law. In contrast to civil law (which is based on a rigid code of rules), common law is based on broad principles. And whereas every defendant who enters a criminal trial under civil law is presumed guilty until proven innocent, under common law he or she is presumed innocent until proven guilty.

Sir my understanding is law should lead to greatest human welfare.

There are two different meanings for 'common law' 

1. is the general legal system inherited from England - so Canada, Australia, US etc have common law legal systems. 

2. the other meaning is the law made by judges, as opposed to legislated by the government. In common law systems, judges have the power to make laws through their decisions. So, when a judge decides that, in this case, X should get damages because reasons ABC, this is common law. The next time there is the same situation, other judges will follow previous judges' decisions. That's called precedent, but that's another story...