The United Nations was conceived in 1941 by the United States, the United Kingdom and the former Soviet Union, and as WW2 progressed, its scope and membership expanded.
By 1945, fifty nations had signed the UN Charter. It's purpose was to promote peace, human rights and international law, encourage social progress, higher living standards, and to prevent another world war.
So the UN was apparently founded on good intentions, but like all motives surrounding postwar settlements, it was mixed with some less elevating concerns. No nation gives power away, and those who had constructed the UN, were very careful to ensure that it reinforced their global pre-eminence.
The supremo arm of the UN is the Security Council, charged with the prevention of war, and can use whatever measures are necessary to force any beligerent nation to desist. The Security Council can, for example, order a ceacefire, levy economic sanctions, send in peacekeepers, or authorise the armed forces of member states to take military action.
The Security Council mimics the notional constraints of the democratic states. By this means it claims to sustain world order founded on right rather than might.
The problem with the postwar settlement is that those with the might, decide what is right. The Council is made up of 5 permanent members -Unsurprisingly, the 3 founding nations (US, UK and USSR -now Russia), and 2 of their principal wartime allies (France and China), and have granted themselves the ability to determine who is the aggressor and who is the aggressed.
All five have veto rights, which has proved to be an instant recipe for abuse of power and an impediment to justice. The US has used it's veto on 11 occasions 1990-2001, six of these halted UN resolutions intended to restrain Israel's treatment of the Palastinians. Member states know that there is no point in preparing a resolution which the US will reject. The US, and to a lesser extent the other permanent members, assert their will without even having to ask.
Other nations cannot hold them to account, the five permanent members (especially the US, and until 1989 the USSR, wielded the real power) can blithely defy every principle the UN was established to defend. Since 1945, the US launched over 200 operations, most of which were were intended not to promote world peace, but to further it's own political or economic interests. The five permanent members of the Security Council also happen to be the biggest arms manufacturers and dealers, and indirectly responsible for exacerbating many of the conflicts the Security Council is supposed to prevent.
The five nations which possess the the exclusive power to decide how threats should be handled, are the five nations which present the gravest threat to the rest of the world.
The UN Charter also grants the five permanent members veto rights over constitutional reform of the UN (Articles 108-09). Even if every other member of the General Assembly votes to change the way the UN works, their decision can be overuled by a single permanent member. Also any one of the five can block the appointment of the UN Secretary-General, election of judges to the International Court of Justice, or admission of a new member to the UN.
The General Assembly has many rotten parts too. There, one nation has one vote, so, for example, the 10,000 inhabitants of the Pacific island nation of Tuvalu has the same voting rights as the 1,000,000,000 people of India, Tuvalu's vote in the UN is weighted 100,000% So we have the joke of when the 'Prohibition of Chemical Weapons' or the 'International Whaling Commission' takes a vote, the small or weak nations are bribed or blackmailed by the rich and powerful to obtain the votes they need.
The UN is inherently incapable of representing the common interests of all the people of the world. There is strong argument, for example, for severly restricting the freedom of financial speculators, whose activity have in recent years wrecked several former healthy economies and contributed massively to the indebtedness of the poor nations. But because of the power these speculators possess to strip a nation of it's financial assets, they have become kingmakers.
Nearly all the governments in power today are those whose policies are acceptable to the financial markets: they are, in effect, the representitives of global capital.
SOURCE: Freely transcribed from "The Age of Consent". by George Monbiot, pages 68-75. Used without permission.