> The German Lander are a better comparison, because the Canadian and Australian states were created at the same time as those countries.

The Canadian provinces and Australian states were pre-existing self-governing British colonies, and are legally (under domestic law) considered to be continuous with those colonies. When the Colony of New South Wales became the State of New South Wales on 1 January 1901, initially very little changed – the colonial government became the state government, in fact it was the same thing, they just replaced the word "colony" with "state". Gradually, certain powers were transferred – over time, the Australian states lost some of their powers which were taken over by the federal government; concurrently, London gradually gave up the powers which it had over the Australian colonies/states, either passing them to the federal government, or the states. It was a slow process over decades, and is generally not viewed as having been officially completed until the Australia Acts of 1986, which formally terminated the UK Parliament's legislative power over the Australian states (which however had de facto fallen out of use decades earlier).

Also, under Australian constitutional law, the Australian states are considered "sovereign", albeit the term is understood differently than in US or German law – sovereignty comes from the Crown (the British monarchy), and the states are sovereign because their governments have a direct relationship with the Crown which acts as their formal head, separate from the federal government's relationship. In a certain sense, the Australian states are more "sovereign" than the Canadian provinces, because their relationship with the monarchy is more direct–Australian state premiers directly advise the monarch who to appoint as the state Governor (the monarch's representative in the state); by contrast, Canadian Lieutenant-Governors (the monarch's representative in the province) are appointed by the Governor-General on the advice of the Prime Minister.

> More generally, international law doesn’t recognize one kind of “sovereign entity” and demote everything below that to “administrative subdivision.” Sovereign states can cede part of their sovereignty to a federation and yet retain part of that sovereignty, as the US states did, as the EU member nations did, as the members of the Soviet Union did, and as the members of the United Kingdom did

The same word can mean different things in different legal systems. A good example is "treaty", whose meaning under US domestic law is much narrower than under international law. Under US law, something is only a "treaty" if the President asks and receives the Senate's consent to its ratification, otherwise it is just an "international agreement". As far as international law is concerned, "treaty" and "international agreement" are synonyms, and the distinction US law draws between them is largely irrelevant.

In the same way, when domestic legal systems such as those of the US or Australia speak of "state sovereignty", they aren't using that phrase in the same sense that international law uses it. Nevada is a "sovereign state" under US constitutional law, New South Wales is a "sovereign state" under Australian constitutional law; but neither is a "sovereign state" as public international law defines that term.

> The aftermath of the collapse of the Soviet Union, and the impending dissolution of the United Kingdom (of Scotland secedes) demonstrates that these sub-federal boundaries continue to have meaning.

As long as sub-national boundaries remain sub-national, international law doesn't care about them. The moment they become national boundaries instead, international law suddenly starts caring. When independence occurs – which is primarily a factual rather than legal question - the status that entity had under domestic law prior to its independence has no international legal relevance. The US has "sovereign states" such as California and "non-sovereign territories" such as Puerto Rico; suppose the US suddenly breaks up, and both California and Puerto Rico become independent sovereign states – the fact that one used to be "sovereign" under US law and the other wasn't, has zero relevance to international law; from an international law viewpoint, they are both now sovereign, but prior to their independence neither was.

Similarly, whether a newly independent state is regaining its past independence, or has never been independent before, has little or no relevance under international law-as far as international law is concerned, prior to its independence, there was no "state" (in the international law sense); and when a state regains its independence, it is not always considered legally to be a continuation of the earlier state (whether or not it is really depends on the circumstances of the case, and whether other states choose to treat it as one or not). From an international law viewpoint, if Scotland becomes independent, effectively that is a new state called "Scotland", lacking any direct legal continuity with the former state of the same name

The boundaries between EU member states are within the scope of international law, because they are inter-state boundaries; the boundaries between US states or Australian states are outside the scope of international law, because they are intra-state boundaries, in the international law sense of "state".