What are the limitations on the structure of a US state government?

Question

Upon a quick scan of the U.S. Constitution, the only direct reference I find as to how state governments are to be structured is in article IV, section 4:

"The United States shall guarantee to every State in this Union a Republican Form of Government..."

Aside from this, there are numerous references to state governmental entities, but no explicit prescription for their structure, powers, or even existence (nowhere does it say "Each state shall have a legislature," for example). I'll list the ones I found below.

• Article I, Section 3.1: Legislature
• Article I, Section 3.2: Legislature, Executive
• Article II, Section 1.2: Legislature
• Article IV, Section 2.2: Executive authority
• Article IV, Section 3.1: Legislature
• Article IV, Section 4: Legislature, Executive
• Article V: Legislature
• Article VI, Section 2: Judges
• Article VI, Section 3: Members of legislature, executive and judicial officers
• Amendment VI: Jury of the state

What is meant by a "Republican Form of Government", and does a reference to a state governmental entity equal a requirement for its separate existence? Fundamentally, what are the hypothetical limits on a state government's structure?

Answer 1

Generally speaking, a republican form of government is any government in which power is indirectly vested in the citizens of the state. It differs from democracy, in which power is directly vested in the citizenry, and from aristocratic, monarchic, and oligarchic forms of government in which power is vested in an elite, non-delegate class.

There are a broad range of political systems that qualify as republics (and a broader range still of systems that present themselves as republics without meeting the basic principle). Republics most commonly organize around a small number of political bodies that are meant to be both deliberative and representative, whose members are usually (though not always) chosen by the citizenry. The US Founding Fathers were particularly concerned by the possibility of factions grabbing controlling shares of power to create tyrannical rule, and so advocated for systems in which power is distributed widely to create checks and balances. Most US states have followed suit, more or less, though the principle does not always extend itself to local levels of government.

The Courts and Congress have a certain say in deciding whether any given system qualifies as a republic, so should a new state be added to the union (or a current state decide to rewrite its own constitution), the federal government could intercede. However, there is nothing that expressly forbids a state from trying to create (say) a religious republic modeled on the Islamic republic of Iran, a soviet-style socialist republic, or any other putatively republican system. So long as the state can justify that power is truly vested within its citizenry, and can comply with federal law on all other points, it would technically qualify. That being said, US political culture is deeply attuned to democratic voting institutions as a primary form of choosing representatives, and deviations from that norm would cause (shall we say) a good deal of stress for everyone involved.

Answer 2

In the United States, all states are sovereign with respect to each other, and are subservient only to the limits specifically placed on them by the federal Constitution (as reiterated by the 10th Amendment). The Constitution does outline numerous powers that are prohibited of the states, but there are no limitations on the structure of each state's governmental institutions or the way powers are organized between them. The references you identified are merely assumptions that separate legislative, executive, and judicial organs would exist in each state. Not because the Constitution mandates them, but because they are a basic feature of all governments in some form. Even authoritarian dictatorships like China, North Korea, and Venezuela have lawmaking assemblies and court systems that they like to pretend are separate and independent.

As for the republican form of government, it should be noted that the Constitution makes a distinction between the people (e.g. "citizens of the several states"), and the states themselves as entities in their own right. What's true of the rest of the constitution is also true here; it should be interpreted as a limitation of federal power over the states -- that each state is guaranteed fair representation in the federal Congress -- not as a mandate for how they are to organize their own government.

When new territories are being considered for statehood, Congress has the power to establish the terms to which they will be admitted (and that implies a soft power to review how that state will organize its powers under its own constitution), but once a state becomes a State, it's a free and sovereign entity like all the others and can amend its own constitution however it wishes (so long as it satisfies all the requirements imposed on it by the federal Constitution).