Yesterday the Tenth Circuit voted to deny en banc review in Kerr v. Hickenlooper. Judges Hartz, Tymkovich, Holmes, and Gorsuch dissented.

To recap, the Guarantee Clause is located in Article IV, Section 4 of the United States Constitution, and provides that “[t]he United States shall guarantee to every State in this Union a Republican Form of Government….”

Other than ensuring that no hereditary monarchy can be established in any of the States, it’s not clear what else the Guarantee Clause does, and the Supreme Court has previously held Guarantee Clause claims to be non-justiciable under the political question doctrine.

In March, however, the Tenth Circuit ruled that the political question doctrine did not bar a Guarantee Clause challenge to Colorado’s Taxpayer Bill of Rights (known as TABOR), which requires voter approval of any new tax or tax increase. The challengers’ claim is that TABOR is unconstitutional because it removes the core legislative power of raising taxes from the state legislature and grants it to the people. The Court also ruled that five Colorado state legislators have standing to challenge TABOR because it dilutes their power. I wrote about the decision here.

You should also read this post by Prof. Derek Muller of Pepperdine Law School, who discusses yesterday’s decision at his excellent Excess of Democracy blog.

It’s not clear to me why voter approval of new taxes and tax increases would be “un-republican.” Many states allow their citizens to vote on ballot measures to enact ordinary laws or state constitutional amendments. Will ballot initiatives and referenda now be subject to challenge in federal court? If not, how can we say that initiatives and referenda are “republican” while TABOR is “un-republican”? Judge Gorsuch makes this point (much more eloquently) in his dissent, arguing that there are simply no judicial standards by which a Guarantee Clause claim can be evaluated.

Judge Tymkovich’s dissent makes the point that the panel’s logic could subject almost any state constitutional amendment to a challenge by disgruntled legislators arguing that the provision dilutes or nullifies their legislative power. Thus, for example, Judge Tymkovich cites the Colorado Constitution’s protection of the recreational use of marijuana. Legislators could attack that amendment “on the theory that the provision infringes on the legislative core function of codifying the criminal law.”

I am surprised that en banc review was denied. The Tenth Circuit’s decision strikes at the heart of the relationship between the federal government and the States, and opens the door for federal courts to supervise and overrule the States’ legislative processes in previously unimagined ways. I think this case has a good chance of ending up at SCOTUS.