The international response to the crisis in Libya has been remarkably quick and decisive. Where many other cases of mass atrocity crimes have failed to generate sufficient and timely political will to protect civilians at risk, the early response to Libya in 2011 has shown that the United Nations Security Council is able to give effect to the ‘responsibility to protect’ norm. While not an implementing party in a legal sense, the Australian government has taken a forward-leaning diplomatic stance in helping to mobilise broad support for addressing this crisis. In light of the ongoing political controversy over armed humanitarian intervention, the Libya case shows that state-based advocacy for R2P matters, given the on-going need to bolster the legitimacy of the principle. A discussion of Canberra’s diplomatic activity is a prelude to an examination of the proceedings of the UN Security Council and the two key resolutions, the second of which gave effect to the forcible action. The article then considers three dimensions of the Security Council’s implementation of the responsibility to protect: the language of the resolutions and the intriguing absence of a textual reference to the international community’s responsibility to act; the expansive mandate for civilian protection in Security Council resolution 1973; and the first unanimous referral to the International Criminal Court, with novel support from the United States of America.