They all voted not only to impose sweeping sanctions on Libya's rulers but also to refer the situation in the country to the international criminal court (ICC) for investigations into possible crimes against humanity.
It is difficult to remember the last time the security council acted so quickly and unanimously in response to allegations of serious international crimes. Never before have the US, China and India, none of whom are party to the ICC - and indeed who had all campaigned against it in its early days - publicly supported the involvement of the court in investigating crimes in a non-member state. (The US and China both abstained on the 2005 vote on Darfur, the only other time a situation was referred to the ICC by the security council.)
Certainly it was the first time a state's own representatives to the UN, who had announced that same day they could no longer represent Muammar Gaddafi's government, publicly asked for the ICC to be given the power to investigate crimes in their country.
Yet some have dismissed the vote as irrelevant to Gaddafi and his remaining commanders, or argued that the resolution itself prevents any investigation into non-Libyan "mercenaries" who some allege have been involved in the killings.
Such responses miss the point. The resolution does not prevent an investigation into non-Libyans. It says only that the ICC will not have jurisdiction over nationals of non-ICC parties if they were carrying out acts in Libya under security council operations (eg peacekeeping). The US insists on this exclusion. It would be better if it were not there, but given there are no UN peacekeepers in Libya, it doesn't matter.
The ICC can investigate and determine the exact involvement of foreigners in Libya in any crimes against humanity, and prosecute those responsible. With the reach of the ICC stretching at least to all its 114 member states, it has more power than other forms of justice to track them down.
Critics of the resolution are right that no one responsible for the crimes is likely to appear in The Hague next week. The wheels of international justice still turn slowly. But increasingly, turn they do, and Radovan Karadzic, for example, has finally been brought to trial after 12 years on the run.
Although we know hundreds have died in the last two weeks, a criminal investigation is needed to determine if this was a crime against humanity - murders that were widespread or systematic, and part of a state policy.
More speed is needed to match the pace of the security council. But the day before the security council voted, the UN's human rights council passed probably its toughest resolution in its five-year history, including setting up a commission of inquiry. It is vital that this commission acts quickly and goes to Libya very soon so it can obtain evidence and identify witnesses for future trials.
Most importantly, everyone in Libya, especially those who remain in power, needs to be aware that for once the international community has spoken with one voice in saying there will be justice for these crimes.
Anyone responsible for an international crime, including crimes against humanity in Libya since 15 February (the day the protests started), is now subject to the ICC. Those who may end up in The Hague are not just those who carry out the deeds. The jurisdiction extends to those who give the orders, up to Gaddafi himself, and also includes those who incite such crimes, and commanders who should know about such crimes and fail to prevent or prosecute them.
If crimes against humanity are being committed, commanders may not sit back and do nothing. Neither will obeying orders to carry out such crimes be a defence.
It is not just Gaddafi but all his commanders who need to be aware that any involvement in international crimes in Libya from now on will put them at risk of trial and imprisonment.
Clive Baldwin is senior legal advisor at Human Rights Watch