The concept of dual sovereignty explains why states cannot secede from the Union unilaterally (unless they do it anyway). It also explains some interesting aspects of recent marijuana legalization initiatives.
Under this doctrine both individual states in the United States are sovereign, as well as the federal government. The federal government only has limited powers (or at least it’s supposed to), but within those powers, federal laws take precedence over state laws. But states are not mere subdivisions of the national government, and the federal government cannot (directly) order state governments what to do. (In constitutional law terms this means that state governments cannot be “commandeered.”)
Operationally, this means that while states are free to enforce federal laws if they wish, the federal government cannot require them to. So a state could legalize marijuana, for instance, and direct all of its employees (including cops and judges) to treat marijuana as legal. The federal government remains free to have its own police (the FBI, the DEA) make marijuana arrests, put people in its own jails, and try them in its own courts. But it can’t make states do its dirty work for it (except through indirect means, such as only giving money to cooperative states).
Washington and Colorado have both legalized marijuana under their laws. The initiatives include certain provisions regarding the regulation and taxation of marijuana. There’s an argument that these regulatory provisions conflict with federal law, since the regulation of marijuana is dealt with comprehensively under the Controlled Substances Act. Therefore it would be said that the federal government “occupies the field” and state laws on the matter are all preempted. If this argument carries the day, and I have no prediction as to whether it will, then these components of the voter initiatives cannot go into force.
By contrast it is hard to see a legally plausible argument that the bare state legalization of marijuana, or state’s declining to enforce federal law in this area, conflicts with federal law. Again, states have no obligation to help the federal government enforce federal law. They just can’t get in its way.
(As an aside, usually only those specific portions of a law that are preempted become inoperative, not the entire law. This is the severability doctrine. But a law might not be coherent if only parts of it are struck out. Or sometimes a judge will find that voters or a legislature intended that either the entire law stands or the entire law falls, or specifically intended the different parts of it to be severable such that if is specific provision is struck out the rest are still in force. But this sort of mind-reading is not necessary when a law specifically states whether its component parts are severable or inseverable. In the case of the Colorado law at least, the law specifically declares itself to be severable. Therefore the voters intended it to be so, which means it is.)
One a similar matter relating to the relationship of states to the federal government, the American Conservative has run a piece recently about the secession of states. It is very scholarly and makes some very good points but it misses some fairly basic ones.
It is true that the people of the state of New Jersey are sovereign and have instituted the New Jersey state government to exercise that sovereignty. But the federal government does not derive its sovereignty from the states, but from the American people as a whole. It is as independent from the states as the states are independent of it. The people of the state of New Jersey or of any state can no more separate themselves from the American people and withdraw from the federal government, than the people of Morris county can separate themselves from the state of New Jersey. When it comes to the indivisibility of the United States, then, the question of the sovereignty of the states is largely irrelevant. The people of the state of New Jersey, or of Texas, are not a relevant unit when it comes to the integrity of the United States. The only “people” that matters with regard to that question is “the American people.” While the federal system makes it so that one person might be a member of two different sovereign entities, the state and the nation, this does not imply that the people of a state can separate themselves from the rest of the Union. You don’t get to pick and choose which “people” you’re a part of.
This why “the people of Austin” can’t secede from Texas. “The people of Austin” are not a sovereign people for this purpose. Similarly, the people of Texas have no sovereign right of succession, even though the federal system means they can exercise their sovereignty in other ways.
But this is the perspective from within our current legal system. The American Conservative article makes the extremely important observation that,
secession, both *de facto* and *de jure*, is an extra-legal act of self-determination, and once the States have seceded from the Union, the Constitution is no longer in force in regard to the seceded political body.
This is exactly right. Secession is legal if it works and illegal if it doesn’t. Really, the question of whether it is “legal” is meaningless. The secession of the United States from Britain was legal under U.S. law. However it was illegal under British law. Although theorists of international law and of natural law attempt to solve this pseudo-problem this is rather like trying to figure out whether the designated hitter is allowed under the rules of “baseball” generally instead of looking at what rules are in force in the American vs. National leagues. Legal systems like the rules of a game exist on their own terms.
(The American Conservative article also does observe something I’ve always found rather hilarious: that the Constitution went into force in violation of the Articles of Confederation. The Articles state that they can only be changed by the unanimous consent of the various state legislatures. But the Constitution went into force, and the government constituted under the Articles dissolved, when only 9 of the 13 signatory states had ratified the Constitution. Thus under the terms of the Articles the Constitution was an illegal document, at least until the 13th state finally ratified it. But of course the Constitution came into force under its own terms: the terms of the Articles of Confederation have no more legal relevance to the Constitution than the Code of Hammurabi. Or, you could argue that the Constitution retroactively invalidated the portion of the Articles that required unanimous ratification. It doesn’t matter.)
With this backdrop the question of whether New Jersey or Texas can secede from the union is legally meaningless, since it’s a political (and perhaps military) issue and not a legal one. Whether states are “sovereign” or not has nothing to do with it, not least because sovereignty is a concept that only has meaning from within a particular legal system, as opposed to being some outside principle that justifies the existence of a legal system to begin with. (Convenient fictions of international law aside.) If a state succeeds in seceding, that means that the sovereign people of that state successfully exercised their sovereign right of self-determination, and good for them. But if they fail, that means that the people of that state all along never even were a sovereign unit with respect to the question of succession, just as the people of my house have no sovereign right to secede from the state of Maryland.