As we have seen, Kelsen identified a fourth function of government, preservation of the constitution, and assigned it to a new institution, the constitutional court. The reason was that in a party-political world neither the legislature nor the executive could be trusted to perform the function except under specific, and probably unusual, conditions. Absent those conditions, legislatures controlled by one party would not investigate threats to the constitution posed by an executive of their own party, and would exaggerate the threats posed by an executive of the opposition party – and conversely, with executive oversight of threats posed by the legislature. Call this a problem of conflict or convergence of interest.