Can a constitutional norm be unconstitutional? This idea seems, at first sight as a self-contradiction. Unconstitutionality is commonly referred to those ordinary laws, inferior to the constitution, which violate it. Constitutional norms, in contrast, carry an equal normative status as the constitution itself and other constitutional provisions. The question of unconstitutional constitutional norms recently arose in the Czech Republic. On 10 September 2009, the Czech Constitutional Court declared Constitutional Act no 195/2009 Coll, on Shortening the Fifth Term of Office of the Chamber of Deputies to be unconstitutional. The Czech Constitutional Court held that the constitutional act was an individual, specific decision and retroactive, thus violating the unamendability provision (Art 9(2)) in the Constitution, which prohibits amendments to the essential requirement for a democratic state governed by the rule of law. This article analyses the Czech Constitutional Court’s decision in a broader comparative and theoretical perspective and focuses, mainly, on four issues: first, the Czech Constitutional Court’s authority to substantively review constitutional norms; second, the appropriate standard of review when exercising judicial review of constitutional norms; third, the ‘individual, specific’ character of the constitutional act; and fourth, its alleged retroactive application. The article claims that while the Czech Constitutional Court was generally correct in claiming an authority to substantively review even constitutional norms, this was not the appropriate case in which to annul a constitutional act.