The subject of this research is ADIn 4.209, judged in March 2012 by the Federal Supreme Court. On that occasion, the Court - in less than 24 hours - changed its own decision, which considered the provisional measure that had created the Chico Mendes Institute for Biodiversity and Conservation or ICMBio to be unconstitutional. Apparently, the Supreme Court didn’t realise that hundreds of other Provisional Measures suffered from the same flaw: they hadn’t been preliminarily examined by a Joint Committee of Deputies and Senators, as required by the Constitution (Article 62, §9). This meant that, in theory, all this legislation, which even created important government programmes, could be challenged. Faced with an intense reaction in Congress and other areas of the public sphere, the Supreme Court backed down. In a technically controversial way and resorting to a so-called 'consequentialist' interpretation, the Court modified the understanding it had established the day before.