Divided and unable to act decisively on the wars in Syria, Ukraine and Gaza, the United Nations Security Council is suffering a worsening credibility problem. This week, French Foreign Minister Laurent Fabius is using the U.N. General Assembly to lobby for an plan to reverse this trend that France’s President François Hollande first floated in the same forum last year. Paris wants a gentlemen’s agreement among the council’s five veto-wielding permanent members — China, France, Russia, the United Kingdom and the United States, collectively known as the P5 — not to veto resolutions meant to halt mass atrocities.

The proposal, which will be discussed by Fabius and at least 20 other foreign ministers on Thursday evening, is based on a moral appeal to circumvent geopolitical stalemate in moments of dire human need. On four occasions since the Syrian conflict began in 2011, China and Russia have vetoed resolutions backed by the West aimed at putting pressure on Syrian President Bashar al-Assad. Many have argued that had the U.N. engaged more effectively early in the conflict, when violence was still relatively limited, that might well have averted its escalation into a civil war, now in its fourth year, that has killed more than 191,000 people. But Moscow and Beijing used their veto power to stall any serious efforts to bring Assad to heel — or even an arms embargo against the regime.

Unlike Security Council reform that would require formal changes to the U.N. charter, veto restraint could be informally agreed overnight if the P5 wished it. France emphasizes that this would be a “voluntary commitment” rather than a legally binding one.

Although Hollande’s concept has won the backing of states from Mexico to Liechtenstein, it is unlikely to become a reality soon. Beijing and Moscow, viewing the proposal as a rebuke for their behavior over Syria, want nothing to do with it. When France co-hosted a meeting on the issue at New York think tank the International Peace Institute earlier this year, no Chinese or Russian diplomats showed up.

The U.S. is almost equally skeptical. While it has only rarely used its veto since the Cold War, it typically does so to block criticisms of Israel. U.S. officials worry that other powers would insist that Israeli military operations, such as this summer’s bloody incursion into Gaza, qualify as mass atrocities. French diplomats have calculated that the current U.S. ambassador to the U.N., former human rights activist Samantha Power, will not want to kill the idea of veto restraint outright. But Washington may be quietly relieved that China and Russia will stymie the plan.

Some supporters of the proposal argue that France and the U.K. should unilaterally promise not to use the veto in the face of mass atrocities. But in Moscow, Beijing and other non-Western capitals, this could be a seen as a signal of weakness by the European powers. Paris and London are already hardly as significant in world affairs as they arguably were when the U.N. was founded. Publicly promising not to use the veto, however laudable their reasons, could make them look like second-class members of the P5.

While veto restraint is likely to be confined to the realm of theory for the foreseeable future, Thursday’s meeting will nonetheless entertain questions over how it would work.

How, for example, would the agreement be triggered? At what point does violence reach the level of mass atrocities, and can this be measured objectively? In mid-2011, when France and Britain first called for U.N. action on Syria, Russia simply responded that Assad had to act forcefully to keep order. Meanwhile, the U.S. holds that Israel’s actions in Gaza are ultimately justifiable acts of self-defense — a stance that makes other members of the P5 uneasy and many U.N. member states angry.

French diplomats have tried to resolve this dilemma in advance. Options include asking U.N. Secretary General Ban Ki-moon or the International Court of Justice (ICJ) to pronounce on whether instances of violence amount to a mass atrocities. These solutions may not convince skeptics. The secretary-general is a diplomat rather than a judge, and Ban in particular has been nervous about offending members of the P5. The ICJ is good at handling protracted international disputes but takes months or years to do so. It is not designed to weigh in rapidly or decisively when lives are at stake.

Resistance to the idea is grounded in fears of what actions might be justified in the name of a U.N. designated mass atrocity. China and Russia have still not fully recovered from the Libyan affair in 2011, when they refrained from vetoing a Western-backed U.N. resolution approving military action to protect civilians and calling for a negotiated political solution to the conflict — and then watched NATO use that resolution as legal cover for a campaign to overthrow Col. Muammar Gaddafi.

Since then, when U.S., British or French diplomats have argued that the Security Council has to act to prevent massacres, their Chinese and Russian counterparts smell a rat. Some states that felt burned by the 2011 campaign feel that if Paris really wanted to secure support for veto restraint, it would make a parallel commitment that any armed intervention directed at regime change would require separate explicit authorization.

It remains highly unlikely that NATO politicians or generals would accept such constraints. And no member of the P5 will sign on to an agreement that truly curtails their freedom to maneuver in negotiations over unpredictable future crises.

This does not necessarily mean that Fabius is wasting his time in New York this week, however. Even talking about veto restraint contributes to the growing sense that the U.N. cannot let mass atrocities go unaddressed. Beijing and Moscow have voted in favor of two very detailed Security Council resolutions demanding greater humanitarian access to Syria this year. Chinese officials in particular seem keen not be cast as bad guys.

The Security Council, by its nature a messy and sometimes dysfunctional body, still gets a lot done despite itself. Last week it passed an unprecedented resolution to tackle Ebola in West Africa. Despite its limitations and the notion that it gets nothing done, the Security Council remains the go-to institution for governments looking to respond to international crises. That’s because it’s the only forum available for seeking multilateral action.