Can we start a discussion on Common Law US. There is a lot of items that are not cover under Law.

I think discussions - pros and cons - belong on discussion boards, unless this is about something specific.

Common law marriages, a few states still allow it ?

But the US is not under "common law" while it is studied in first year law school ( still don't know why honestly) US law is by statue and court interpretation of the law. Some arguments on interpretation may be done using common law or even laws of other natoins.

I see little reason to discuss a system not really used in US

... But the US is not under "common law" while it is studied in first year law school ( still don't know why honestly) US law is by statue and court interpretation of the law. Some arguments on interpretation may be done using common law or even laws of other natoins.

I see little reason to discuss a system not really used in US

That's what the Common Law is: "... interpretation ... done using common law or even laws of other natoins." Answering questions not specifically addressed by statute by looking to what other courts have said the common law is. It's very much a part of American jurisprudence.

And if this forum is indeed an international one, even if it weren't used in the U.S. it would be pertinent. Although, as JudyKay Tee said, general discussion of law is not what this forum is about.