Last week, the 10th Circuit held that the plaintiffs in TABOR do have standing. Taxpayers may not, the court ruled, but members of the legislature are injured by TABOR. "With respect to taxing and revenue," the panel wrote, "the General Assembly allegedly operates not as a legislature but as an advisory body, empowered only to recommend changes in the law to the electorate." Some earlier cases have permitted legislators to challenge procedures that "nullify" their votes, and TABOR does that, the court reasoned.
As for the "republican" issue, the panel noted that the Oregon case is not the final word. The Supreme Court in 1962 decided that state apportionment rules are not "political questions"—thus opening the way for decisions requiring "one person one vote." The TABOR case doesn’t challenge the lawfulness of the existing government, and it doesn’t claim that all the state’s laws are void. The 1962 case, Baker v. Carr, laid out a list of factors for determining whether a case is "political"; most of those deal with relations between the courts and other branches of the federal government. For a federal court to interfere with state constitutions is far less unusual, and it is legitimate under the Supremacy Clause of Article VI § 2. In a 1992 case, Justice O’Connor dropped a broad hint that some members of the Court might be interested in exploring claims under the Guaranty Clause. For all these reasons, the 10th Circuit said, a federal court could decide whether TABOR is "republican."
The panel opinion didn’t decide that issue. In theory, what would follow is a trial in front of a district judge, where the plaintiffs could put on evidence of the damage TABOR is causing. However, state Attorney general John Suthers could ask the entire court to review the case "en banc," or he could petition the Supreme Court for immediate review—or both. (So far he hasn’t announced a decision.)
Either move might open the plaintiffs’ case to new critique. So far, by the luck of the draw, their claim hasn’t faced the scrutiny of a single Republican judicial appointee. GOP appointees tend to be more conservative, and more protective of states, than their Democratic-appointed counterparts. O’Connor is no longer on the Court, and her replacement, Samuel Alito, is quite sympathetic to state government.
As a con-law nerd, I’m rooting for a trial. A state whose legislature can never pass a tax strikes me as a kind of anarchy ruled by sporadic popular vote, rather than anything that qualifies as representative government. The Guaranty Clause must mean something; if the federal courts can invent a new, completely non-textual rule against the "individual mandate," I am not sure why they should ignore the specific words of the text. If you think that the states should be immune to federal interference, think again. Don’t blame me—blame the Framers.