"The standards for proof should be equally applied, whether we're talking about Saddam Hussein, OJ Simpson, Earth or Mars, and each case should be judged on its own merits."

This is obviously not true.
In science you are have a scientific method, ect.
In a court (US civil) the accused is innocent until proven guilty; the accused must be violating a specific law, and there are a number of protections for the individual vs the power of the State. And in general there is a number of different laws and procedures depending on the parties involved and the severity of the suspected crime.
International law is depended upon agreements reached between nations. There is no absolute body which can judge or execute any judgements.

So in science there is no judge or jury which can pass judgements on science. In US law, generally you are entitled to a judgement of a jury of your peers {you also have an appeal process if judged guility}. In international law it's mainly how countries interpret agreements which they have agree to. There is no higher legal authority then the soveignity of each nation. Nation can submit their authority to agreements they make with other nations, but agreements can be broken any nation that enters into them. The right to declare war on any nation is a right of any nation. Under the UN, a nation has right to attack any nation if there is a perceived and immediate threat (or nations can join with other countries which is threaten by another country.)
Hostility between nations can continue, or agreements can be reached which determine the type of peace between countries. Breaking agreement between nations can have serious consequences, they can also be ignored by parties involved. In signing a peace agreement parties are making various agreements which bring about a ending of hostility, breaking this agreement can result in a resumption of war. Iraq made an agreement to give it's Weapons of Mass Destruction- and this would be verified by an international body. And because Iraq did not, has not, and will it fulfill this agreement, the US is invading Irag to change the regime.