First, let's talk about what international law IS before we go about figuring out its limitations. Stated simply, international law has the purpose of letting many nations keep the peace, protect human rights, and maintain productivity in both business and personal affairs.
International Law is the set of rules generally regarded and accepted as binding in relations between states and between nations. It serves as a framework for the practice of stable and organized international relations. International law differs from state-based legal systems in that it is primarily applicable to countries rather than to private citizens.
There are MAJOR limitations here. Mostly, each country is a sovereign unto itself, so it is not binding with domestic governments! In other words, international law is always just a "suggestion" and contains no "world police" to enforce its rules. Even though there is a declaration of human rights that is universal, the only way infractions can be enforce is if a group of countries agree to enforce it. This is often the way the United States gets blamed for "unilateralism."
The United Nations is a perfect example. The enforcement procedures are maintained through the Security Council. There can be loss of legal rights and privileges within the UN and, if countries agree, peacekeeping forces can be sent to different countries, but there are so many countries with so many cultural differences, the UN is often rendered "useless."
Let's create a simply list as to why. These, then, are the main limitations of international law:
- need for consensus
- no single international "ruler"
- no enforcement mechanism ("world police")
- lack of funding
- vast differences in cultures, no real "norms"
Perhaps ICJ (International Court of Justice) could be considered a successful organization of international law. At least this body can make decisions in regards to serious war crimes. (Milosevic is an example). Decisions aren't binding, though. So the limitations above still hold true. Further, there are too many dictators and other soverigns that simply ignore the international law organizations and, because there is no enforcement, they can get away with it.
Therefore, unless legislation under international law is enforced by domestic legislation (in a particular country) there is no one to enforce it unless a huge consensus is reached in international law agency, such as the UN. Therefore the fight for world-wide human rights continues to be an issue in many areas around the world.