Standard domestic cats are legal in Hawaii. Wild cat hybrid domestic cats are illegal in Hawaii. This is a reference to Bengal cats and Savannah cats for instance. There are other wild cat hybrids which you can refer to by clicking this link. And secondly, genuine wild cats such as the caracal and serval which are sometimes tamed and semi-domesticated as pets on mainland America are also illegal in Hawaii on my understanding of the law.
My research indicates that the Hawaii government ban Bengal cats because they believe they pose a risk to native birds and because they may carry a parasite which harms the monk seals, a native species to Hawaii. They don’t state what this parasite is, but it might be a reference to Toxoplasma gondii which affects any domestic cat. So, at present, I’m not clear about this mysterious parasite. Logically, as Bengal cats are the same as any other domestic cat at a fundamental level, if they carry a parasite, then other domestic cats will carry the same parasite.
And the ban on Bengal cats and Savannah cats and other wild cat hybrids refers to all of them not just the high filial cats by which I mean F1-F3. In some states in the US first filial wild cat hybrids are banned (New York State) but the F5 is considered to be very similar in behaviour to a regular domestic cat and therefore there is no need to ban them.
The reason why Hawaii is more sensitive to protecting their native species is because it is my belief that they rely on them for tourism. It is similar to the attitude of the provincial governments of Australia where they, too, have banned wild cat hybrids such as the Savannah cat. There was an attempt many years ago to introduce the Savannah cat into Australia by A1 Savannah, a premier breeder, but it failed.
Another reason why wild cat hybrid domestic cats are banned is because they are potentially more aggressive and more successful hunters than regular domestic cats. If they escaped from their home which is not unlikely, they would threaten Hawaii’s native bird species which are a very important resource for the Hawaiian Islands. There is probably also a fear that any escaped unsterilised Bengal cat would mate with feral cats and create a super hunter. Feral cats are a problem to the Hawaiin authorities for their predation on native birds.
If you try and smuggle a Bengal cat into Hawaii, you will be stopped at customs and the cat will be seized. Apparently, a couple tried to import three Bengal cats into Hawaii in 2018. They were not fined but the cats were confiscated and shipped back to the mainland without them. They were not treated as criminals and did not acquire a criminal record. Further, if caught you will have to pay for shipping costs back to the mainland.
I must presume that everything said in the paragraph above applies to any other wild cat hybrid. There may be difficulties on occasions for the customs authorities to assess whether a domestic cat is a wild cat hybrid or not. The Bengal cat is well known, and fairly easily identifiable but other wild cat hybrids are much less well-known and therefore less identifiable.
It is said that for the most part all exotic animals are illegal in Hawaii. Some non-domestic animals are conditionally approved for importation into Hawaii such as rabbits, guinea pigs, chinchillas, rats and mice.
Hawaii has a list of conditionally approved animals which is very long. The cat is a mammal, and this list contains mammals, none of which are cats. They are, as mentioned above, guinea pigs, chinchillas, domesticated mice and rats.
Below are some articles on laws.