USA, during the Clinton Administration, signed, but did not ratify, the Rome Statute of the International Criminal Court on December 31st, 2000 – the last day in which the treaty remained open for signature. It is worth mentioning, however, that, in order for a State to be bound by a treaty, it must - in addition to signing it - ratify it.
Shortly after he was elected President of USA, George W. Bush decided to “unsign” the Statute. As a result, the US “unsigning” sparked controversy in the international community, as this action does not exist in the law of treaties. The situation remains unsolved. But, in any case, the United States of America is not a State Party to the Rome Statute, and has always been reluctant and hostile towards the ICC.
Unexpectedly, the Obama Administration has somehow changed the US attitude towards the ICC, and is now cooperating with it through the Security Council.
Nevertheless, will USA eventually accede to the Rome Statute? Here is an interesting analysis.