Can a U.S State Independently Join the Commonwealth of Nations?

Question

In August California signed a Climate Change Pact with the UK for Carbon Trading, independent of the Federal Government.

Answer 1

By U.S. federal law, a state is not allowed to join an international agreement solely by itself.  It requires the consent of the U.S. Congress.

Answer 2

No, because it is not a nation and lacks the authority to make treaties.

Pacts aren't treaties.

Answer 3

The US State must first secede from the Union before joining the Commonwealth of Nations.

Answer 4

Colonised countries that got its independance, then, formed the Commonwealth  of Nations , while US fought and broke away in 1779.

No outsiders allowed in the Commonweath of Nations.

Answer 5

Not unless it first seceded from the U.S.!