The United States is not a State party to the Rome Statute. I was just illustrating some points made by Professor Quigley - that the United States had recognized the State of Palestine in accordance with the provisions of conventional international law & that it customarily treats States as continuing to exist if their territory is under foreign occupation. The Baltic States provide an example of an undertaking that lasted for many decades.

In cases like Kletter, those routine determinations of statehood continue to have legal consequences in our national courts afterward as a matter of intertemporal law. Palestine remains the "country of origin" for many resident immigrant aliens who came here during the Mandate era. Palestinian nationality or origin also had its basis in the Treaty of Lausanne and is a federally protected characteristic. The ICC exercises complementary jurisdiction. It will produce very strange results going forward if it adopts a different definition of the term "State" than the one currently employed by State Parties to the Rome Statute. 110 or more countries recognize Palestine as a "State" with all the rights and duties determined by international law. The obligation of the Court in making Palestine's Article 12(3) declaration effective has an erga omnes character. It isn't minting new states in a situation where the national courts of other countries already accept the legal personality of an entity as that of another existing state. The ICC is merely perfecting the secured interests of those other members of the international community of states by taking the necessary steps to apply the rules they have adopted for the conduct of their mutual relations..

In 1995 the State Department published a Memorandum of Conversation between William Crawford Jr. and Mr. Shaul Bar-Haim from the Israeli Embassy (February 7, 1963) regarding Jerusalem. Bar-Haim said "The use of the term "Palestine" is historical fiction; it encourages the Palestine entity concept; its "revived usage enrages" individual Israelis". Crawford replied "It is difficult to see how it "enrages" Israeli opinion. The practice is consistent with the fact that, ''in a de jure sense'', Jerusalem was part of Palestine and has not since become part of any other sovereignty. Crawford added that it was not a simple matter since there was a ''quota nationality'', in regard to which U.S. legislation and regulation continued to employ the term Palestine at that time. See Foreign Relations of the United States, 1961-1963, Vol. Xviii, Near East, United States. Dept. of State, G.P.O., 1995, ISBN 0160451590, page 341.

US immigration law still reflects that the trusteeships and mandates were states. U.S. Title 8, Chapter 12, § 1101. Definitions says "(a) As used in this chapter— (14) The term “foreign state” includes outlying possessions of a foreign state, but self-governing dominions or territories under mandate or trusteeship shall be regarded as separate foreign states."

Other treaties contained similar provisions to the ones found in the Treaty of Lausanne. Article 434 of the Treaty of Versailles stipulated that Germany was required to recognize the dispositions made concerning the territories of the former Ottoman Empire, "and to recognize the new States within their frontiers as there laid down." The other Central powers and the treaty articles that required them to recognize the new States were:
*Bulgaria Article 60 of the Treaty of Neuilly;
*Hungary Article 74 (2) of The Treaty of Trianon
*Austria Article 90 of The Treaty of Saint-Germain-en-Laye

So, Palestine was a "state" as defined in national and international law. If you look for bilateral and multilateral agreements between modern-day Palestine and other states, you'll find evidence that Palestine has ratified or signed many other instruments as a "State" in accordance with the terms of conventional international law.