The debate essentially says that ICC prosecutions, which demand justice and accountability, are a roadblock to peace because they eliminate the incentives of parties to a conflict to end it if they think they will be prosecuted, e.g. Joseph Kony in Uganda.
Rachman also notes a well-founded fear:
Some Africans complain that the ICC is using their continent as a laboratory.
For although justice is meant to be blind, it is clear that there are certain
countries and political leaders that are just too powerful to bring before the
court. There will be no prosecutions of Russian leaders over crimes in Chechnya.
And – despite the fears of American conservatives, which have led the US to
reject the court – the ICC is also highly unlikely to prosecute Americans.
While it has flaws, let's hope the ICC stays around as a valuable institution--if only as an expression of our collective values.