The governmental powers must not only be satisfactorily distributed between the Centre and the units, but provision must be made to prevent either from encroaching upon a sphere allotted to the other. Here, again, federations differ in respect of the safeguards provided against this possibility, and their efficacy. The most common safeguard is the establishment of an independent court to interpret the constitution and decide conflicts of jurisdiction between the Centre and units. The American and the Australian courts are the best instances of this ; in Switzerland and the U.S.S.R. the Supreme Court has no power to declare to federal law unconstitutional and, to that extent, the judicial safeguard is ineffective as a means of protecting the rights of the units. A Second safeguard is the power given to the people, as in Switzerland, by the referendum and the initiative to decide finally on constitutional laws, the, i.e. not alterable by the ordinary law-making body of centre or of the states. Invariably, too, some part is given to both the Centre and the in the process of amending the constitution, the U.S.S.R. being an exception in that it ignores the units ; again invariably, the part assigned to the units is greater than that allotted to the Centre. The central Legislature is given the power to propose amendments in the U.S.A., Australia, and Switzerland ; the final ratification by a majority of the units is made essential ( in the U.S.A. by three-fourths of the states). Further, some fundamental rights of the units (as, for instance, the right to equal member-ship in the Senate in the U.S.A., and territorial limits in Australia) are made unalterable except with the consent of the states affected.