I have not posted much on Hawai'i, in part because easily readable information has been difficult to find. Hawai'i's situation is unique. While other States were independent prior to admission to the Union, Hawai'i is the only State to be independent prior to acquisition as a territory. The record shows that the legality of that State's addition is highly questionable. The annexation of Hawai'i to the United States was not a cession because it occurred without the consent of the Hawai'ian government and people, therefore Hawai'i technically cannot secede.
The legal argument is that Hawai'i's is a Republic (or arguably, still a Kingdom) that has been under a 111-year occupation by the United States. Further information is available from the Hawaiian Independence Blog.