Is the ICC effective in holding perpetrators accountable for the most egregious atrocities?

The full question for this paper is: ‘In theory, the ICC holds perpetrators of the most egregious atrocities accountable for their crimes, provides justice to the victims, and deters future abuses. In practice, however, the court has been ineffective, unaccountable, and indeed, outright dangerous.’ (John Bolton, US National Security Advisor, 10 September 2018). Critically discuss the above statement, providing full legal authorities when necessary and appropriate.