resolves constitutional disputes. It also has the authority to give its opinion on any matters that may "gravely undermine the basis of the institutional system" (articles 95 and 96).
The background of the Supreme Court justices also favors the interests of the upper class socioeconomic groups that supported the military government. Towards the end of his rule, Pinochet offered generous retirement incentives to the most senior members to ensure the appointment of relatively young judges who were friends of the outgoing regime. Thus, on constitutional issues, the Supreme Court generally supports the conservative position. For example, it has consistently taken a narrow interpretation of private property rights in which any expropriation—which the state can only undertake for reasons of public utility or national interest—must be compensated at full market value, in cash, and in advance. The Supreme Court's Conservative bias has also hampered the investigation and prosecution of human rights violations during the military government.
The powers of the Senate and the electoral system round out the tether with which the 1980 constitution ties the democratic regime to the free market socio-economic order built by the military government. All legislation must have the approval of both chambers of the Congress. Thus, the Senate can kill a bill if it is unwilling to compromise with the house of deputies. The designated senators generally give Conservatives a majority over supporters of the center-left on core issues. As a result, center-Left governments must compromise strongly with Conservatives, to the point of gutting bills at times, as has been the case with constitutional reform efforts and labor law reform. Even then, when Conservatives do not wish to compromise they simply veto bills. Some analysts have argued that the President of the Republic's capacity to appoint some of the designated senators eventually will change the balance of forces. This may be overly optimistic, however, because the institutions they must be drawn from are notorious for their conservatism.
The electoral system also favors Conservative political forces by overrep-resenting them. First, the boundaries of electoral districts for both the Chamber of Deputies and the Senate were gerrymandered to give more weight to areas that had voted heavily for Pinochet in the 1988 plebiscite. For example, electoral districts for deputies give greater representation to rural areas than urban areas which voted for the democratic opposition. Thus, Santiago, which accounts for 40 percent of the nation's population receives only 26 percent of the deputies. Further, in 1989, twenty rural districts with approximately 1.5 million people elected forty deputies while six urban areas with the same population elected only fourteen. Second, the binomial electoral system also benefits Conservatives in lower house elections. Each district elects two deputies. A party coalition must obtain double or more votes than the competing coalition to win both seats. If it does not, the minority coalition automatically wins a seat. This system ensures that the second highest list, frequently supporters of Pinochet and conservative parties, obtain maximum representation, certainly more than under first past the post or straightforward proportional representation. In other words, the second