The US Senate – usually the Republican members – reject multilateral treaties as if it were a sport. Others it rejects through inaction – the Law of the Sea Treaty, for example, negotiated under President Jimmy Carter and fruitlessly pushed for ratification by every president since. Republicans justify their blocking tactics by arguing that such treaties are a threat to sovereignty.

However, after almighty struggles – it takes only one third of the Senate to block a treaty – the important nuclear arms’ treaties with the Soviet Union and Russia – were ratified. So was the Convention against Torture which Republican president, Ronald Reagan, successfully fought for but which President George Bush junior illegally ignored, without a word of protest from Congress or the press. His vice-president, Dick Cheney, became torturer-in-chief and should have been arrested by the incoming Obama Administration. But Obama, wanting a peaceful life with Congress for the sake of future legislation, decided not to prosecute the torturers.

On Monday this week Syria joined the Chemical Weapons Treaty that the US has long been a party to.

The US must be glad it did ratify it. Once it did there was immediately a flood of other countries doing likewise. Without that ratification there would have been no deal with Russia on abolishing Syria’s chemical weapons’ stocks. Nor would this month’s Nobel-prize winning Organisation for the Prohibition of Chemical Weapons be at work dismantling those stocks today. Everyone, including the Syrians, would have said why should they do anything if America doesn’t itself? The US has dismantled most of its own large stocks and so has Russia.

But, by and large, the US does stall on treaty ratification even it was involved in their negotiation, often playing a benign and crucial role. One example is the Convention on the Rights of the Child – along with Somalia and South Sudan it is the only country not to have ratified it. Yet the Convention stands for the very essence of basic civilised behaviour and its principal conceptualizer and protagonist was a fine American, James Grant, who for many years was the director-general of Unicef.

However, in recent years, the Clinton, Obama and even the Bush administrations figured out ways of circumventing the Senate, sometimes even exercising leadership. In an article in the latest issue of Foreign Affairs, David Kaye calls this “stealth multilateralism”. With the Law of the Sea, which codified customary rules that govern the extent of a state’s sovereignty over its territorial seas, rights of passage, seabed resource allocation, illegal fishing and much else the US acts as if it were binding (whereas China, which has ratified it, seems to be ignoring it in the South China Sea disputes).

The US has refused to ratify the 1988 Rome statute that established the International Criminal Court. Not surprisingly, some delegates at the African Union debate last week over the impending trial of Kenya’s president, wondered aloud why they should remain members of the ICC when the US isn’t. Ironically, when Bush took office, he went out of his way to sabotage the treaty. Later, realizing how useful it was, he changed tack and began to work with it, even consenting to a UN Security Council resolution that referred Sudan to the ICC. Obama has done the same, only more so. Obama has offered million dollar rewards for information leading to the arrest of ICC fugitives. After a Congolese warlord presented himself to the US embassy in Rwanda in March the US quickly transferred him to be detained by the ICC in The Hague. Professor Kaye writes,“The US has arguably become the the court’s most significant supporter”.

Likewise, the US has given significant support to the non-ratified Convention on Tobacco Control. US law has been aligned with the convention. In 1997 the Ottawa Treaty outlawed land mines. It was opposed by the Pentagon on the grounds that mines were critical in keeping the peace on the Korean peninsular. In practice, Korea apart, the US has scrupulously avoided producing, transferring or deploying mines. It leads the world in de-mining projects. It has even helped pay part of the costs of meetings of the treaty’s parties.

Nevertheless, this way of playing it has serious flaws. With the ICC it has made it impossible- if ever it was likely- to detain members of the US armed forces for war crimes, even though American courts have acted unsatisfactorily by ICC standards. Challenges such as climate change are best addressed through ratifying treaties. Many global solutions require the binding force and permanence that only treaties can provide. (If Mitt Romney had won the last election not Obama, he may well have halted cooperation with the ICC.)

The US has lived with its moral ambiguities for so long only a great heroic shove will wake it up.