Today, the Supreme Court heard oral argument in Friedrichs v. California Teachers Association, a challenge to public-sector unions’ ability to extract forced dues from non-members. As my colleague Ilya Shapiro writes, and Ian Millheiser at Think Progress agrees, the Court seems poised to strike down “fair share” fees for public-sector workers who do not want to join the union. This would essentially mean that “right to work” would be constitutionally mandated for public-sector workers.

Such a ruling would correct a 40-year-old mistake the Court made in Abood v. Detroit Board of Education. There, the Court ruled that public-sector union dues can be meaningfully separated into the “political” and the “non-political,” and that, while the First Amendment forbids forcing people to support political causes with which they disagree, public-sector unions can extract a “fair share” fee for non-political purposes.

From the very beginning, this distinction was under attack. As Justice Lewis Powell wrote in concurrence in Abood:

Collective bargaining in the public sector is “political” in any meaningful sense of the word. This is most obvious when public-sector bargaining extends … to such matters of public policy as the educational philosophy that will inform the high school curriculum. But it is also true when public-sector bargaining focuses on such “bread and butter” issues as wages, hours, vacations, and pensions.

In other words, public-sector unions are just another political special interest that seeks favors from the government, and what they can’t get at the ballot box they’ll get at the bargaining table.

Yet, if public-sector unions are just another special interest group, then why does the government give them the extraordinary privilege of extracting dues from non-members? Parents don’t get this privilege. Trade associations don’t get this privilege. Non-profits don’t get this privilege. In fact, unions are the only special interest group in American society that gets this privilege.

The primary argument in favor of forced agency fees is the “free rider” argument–namely, that those who don’t contribute to the union will be allowed to free ride on those who do. But, as pro-union Professor Clyde Summers once pointed out, this is essentially what happens in all types of private associations:

Why is it not applicable to a wide range of private associations? If a community association engages in a clean-up campaign or opposes encroachments by industrial development, no one suggests that all residents or property owners who benefit be required to contribute. If a parent-teacher association raises money for the school library, assessments are not levied on all parents. If an association of university professors has as a major function bringing pressure on universities to observe standards of tenure and academic freedom, most professors would consider it an outrage to be required to join. If a medical association lobbies against regulation of fees, not all doctors who share in the benefits share in the costs.

The government-thumb-on-the-scale, forced-dues privilege that unions enjoy should give us pause. It seems positively un-democratic for the government to grant such an extraordinary privilege to one group, or possibly just un-republican.

The Guarantee Clause, or the “Republican Form of Government Clause,” can be found in Article IV, Section 3 of the Constitution. It reads: “The United States shall guarantee to every State in this Union a Republican Form of Government…” Writing in the Heritage Guide to the Constitution, Rob Natelson, one of the foremost originalist scholars, writes that a “Republican Form of Government” means three things: 1) “popular rule, broadly understood,” 2) no monarch, and 3) the rule of law.

In practice, the Guarantee Clause is one of those constitutional clauses that is so vague it is rendered essentially unenforceable. On top of this, the Supreme Court, in one of its most interesting cases, ruled that the clause is not justiciable by the courts and is therefore only a political question for Congress. That case, Luther v. Borden, concerned the Dorr Rebellion, a virtual coup in 1840s Rhode Island (really).

So my comments here should be read in light of the fact that the Guarantee Clause is severely under-theorized. Yet, it seems not absurd to argue that, if “republican form of government” means anything, it means that the government cannot privilege one interest group over another. This would broadly accord with Natelson’s concept of “popular rule, broadly understood.”

The Guarantee Clause is mostly dormant. It was recently revived, however, by teachers unions and other organizations seeking to overturn Colorado’s Taxpayer Bill of Rights (TABOR). Kerr v. Hickenlooper, in which Cato has filed two briefs, is a challenge to Colorado’s method of raising taxes only through popular approval by the people. By removing tax hikes from representatives, the argument goes, it is no longer a “republican” form of government.

This seems like a stretch, but so is any argument based on the Guarantee Clause. If the Supreme Court preserves forced agency fees for public-sector unions, however, it may be worth looking into whether a Guarantee Clause argument might be made.