He argues that Mugabe's governing negligence has led to Zimbabwe's widespread cholera outbreak -- which has taken over 3,000 lives in less than three months -- that is threatening to drive many infected peoples into bordering countries like South Africa. Based on this, Hitchens claims that Mugabe leads an implicit aggressor state against his neighbors, and under the UN Charter, this is grounds for defensive action (i.e. international intervention to dethrone Mugabe).
But this is a legal slippery slope of black ice, if there ever was one. No matter how negligent -- and he is a terrible leader of his people -- Mugabe did not intend for the cholera to spread like a biological agent via desperate Zimbabwean citizens. Mugabe has no interest in attacking his neighbors.
So if the new precedent is 'unintentional germ warfare' as grounds for invasion, then the implications are frightening. China would be invaded biannually whenever it suffers from an outbreak of bird flu in its southern provinces. Any country could declare war on any other if it could prove that a sick person from a foreign nation had transferred a disease to their own citizens. The US -- with its widely traveled population -- would be invaded by Summer 2009. This is absurd.
It seems like Mr. Hitchens wanted to derive reasons for a conclusion from a pre-determined conclusion. In other words, "Mugabe is a horrible person and should be removed from power, so what evidence can I find to prove my desired outcome?" This is not how reason should work. The evidence should drive conclusions, not the other way around.
All this said, there still may be a case to intervene. The Responsibility to Protect -- an international agreement solidified during the 2005 World Summit -- surrenders a state's sovereignty to the international community if the state's government cannot or will not protect its citizens from genocide, war crimes, crimes against humanity, or ethnic cleansing. Under the Responsibility to Protect (R2P), the horrible economic depression and disease that has continued unabated in Zimbabwe for eight years may be defined as a "crime against humanity". 34-year life expectancy and 200,000,000% inflation is not a societal order; it is a nightmare.
Of course, with the recent political compromise and subsequent swearing-in of Prime Minister Morgan Tsvangirai, it may now be an illegitimate time to invoke R2P. Nevertheless, with state failures like Zimbabwe, we must begin to debate a broader definition of "crime against humanity".
Correction (2 February, 2009): Zimbabwe has experienced 200,000,000% inflation, not 200,000%... as if the currency wasn't worthless enough.