If the UN climate negotiations in Paris are successful this month, it will be because they have overcome a problem.

It’s no exaggeration to call this problem fundamental to what’s happening in Paris—because it goes to heart of why everyone is there in the first place. More than 150 world leaders are gathered just outside the city of lights this week, along with thousands more negotiators, protestors, journalists, researchers, support staff, brand representatives, corporate event organizers, non-profit fundraisers, and security staff. They will hold summits and conferences and public demonstrations, and tens of thousands of people elsewhere on the planet will be watching, hoping (and working) for one outcome or another.

What’s the point of all this?

The easy answer is that they’re all pushing for or leaning on the creation of a climate treaty—possibly the first significant pact in the history of the world’s struggle with climate change. But here’s the thing: Not all the attendees want to actually negotiate a treaty. Some nations, including the United States, would prefer something a little less binding, something like a commitment to voluntarily commit.

France wants a legally binding treaty to emerge from the talks. Francois Hollande has staked much on the talks’s success, telling the press earlier this month that, “If the agreement is not legally binding, there won’t be an agreement, because that would mean it would be impossible to verify or control the undertakings that are made.”

Many developing countries, especially those most threatened by climate changes, have also pushed for legal force. And the wider international community has also promised itself that 2015 is the deadline for a legal pact. In the 2011 agreement in Durban, which began the process currently concluding in Paris, nations agreed to “develop a protocol, another legal instrument or an agreed outcome with legal force” no later than the end of 2015.

But the Obama administration, in its capacity as a regent of the United States, does not want a legally binding treaty to emerge from the conference. That’s because, in truth, not everyone in the United States actually wants a deal. A legally binding treaty would have to affirmed by the Republican-controlled Senate, whose leadership have conveyed in no weak terms that they would never approve a treaty.

So the Obama administration has instead lobbied for a voluntary pact. It can then comply with the terms through domestic executive action (such as its Clean Power Plan) without having to shop a treaty around Congress. U.S. Secretary of State John Kerry has affirmed throughout November that COP21 would not produce a treaty, and the State Department, responding to a Congressional inquiry, has said that the conference “is not intended to constitute an obligation the United States must fulfill under international law.”

So what are they all doing in Paris? And how will the parties at the UN produce an international agreement that both is and is not a treaty?

Obama provided a possible resolution on Tuesday. Speaking at a press conference, the president said that some aspects of the deal could be legally binding. Specifically, the revision timetable—that is, the frequency with which parties meet to agree on new emission reductions—could exist as international law, he said. But the targets and commitments made toward emissions reductions themselves needed to remain entirely voluntary.

“Although the targets themselves may not have the force of treaties, the process, the procedures that ensure transparency and periodic reviews, that needs to be legally binding,” said Obama. “That’s going to be critical in us having high ambitions and holding each other accountable.”

If adopted by the larger conference, this would present an answer to the pesky question of what is being created in Paris. The deal to emerge at COP 21 would bind in its procedures but not its policies, forming a treatylike resolution to keep meeting that would not, in fact, be a treaty in any of its details. (That said, there also isn’t yet agreement on how often nations should meet to revise their emissions targets.)

These kinds of details matter. The world has attempted to ratify a legally binding international climate treaty before: It was called the Kyoto Protocol. Written in 1997, the Kyoto Protocol was adopted by Europe, Japan, Russia, and much of the rich world—it even technically entered into force in 2005— but it is perceived largely as a failure. In 2000, George W. Bush indicated the United States would never sign onto the treaty and would not comply with it. (After his election, U.S. utility companies promptly began planning hundreds of new coal plants.)

Kyoto didn’t work in part because it adopted a compulsory “top-down” approach, where the UN set targets and nations fought over how to meet them. The climate deals that have evolved in this decade, in Durban, South Africa, and Lima, Peru—and which are meant to be locked in at Paris—have taken a different tack, asking for voluntary national emissions reductions and working from there.

If the compromise that Obama outlined Tuesday makes it into an eventual Paris deal, it would, in a fashion, extend this “bottom-up” approach into the nature of the deal itself. Nations would agree to the architecture of a climate treaty, in a way, without locking themselves into much of the content of a deal. That may not sound like much—right now, it's not even enough to prevent the worst of global warming—but it's much better than the status quo.