When President Barack Obama claims, as he did at the G20 summit in St. Petersburg Friday, that the absence of a United States bombing attack against Syrian dictator Bashar al-Assad "threatens to unravel the international norm against chemical weapons embraced by 189 nations, and those nations represent 98 percent of the world's people," he is deliberately blurring the lines between three international treaties to make it look like they require U.S. enforcement.

Not only do these pieces of international law say nothing about granting Washington ultimate responsibility for policing, the United States has a long history of limiting their scope and exempting America from their constraints. In short, the U.S. seeks to enforce the very same norms it has often chafed against, or even rejected.

The three relevant treaties are:

1) The Geneva Protocol of 1925, otherwise known as The Protocol for the Prohibition of the Use in War of Asphyxiating, Poisonous or other Gases, and of Bacteriological Methods of Warfare. This document binds signatories to renounce "the use in war of asphyxiating, poisonous or other gases, and of all analogous liquids, materials or devices," the key phrase here being "use in war." At the time of the signing, and mostly ever since, this was understood as specifically referring to war between states. Domestic usage may be horrific, but it's not covered by the Geneva Protocol.

There are 138—not 189—nations that have signed the treaty, including Syria. In fact, Syria signed it seven years before the United States got around to ratifying the agreement in 1975, and even then Uncle Sam inserted the caveat that it believes this particular international norm "ceases to be binding as to the use of chemical weapons in regards to any enemy state which does not observe the prohibitions of the protocol." That is to say, if those bastards chemical us, we reserve the right to chemical them right back.

So what's the enforcement mechanism? As René Wadlow recently pointed out, "the 1925 Geneva Protocol has no investigative measures and no dispute settlement provisions." There is nothing in the treaty that remotely contemplates a bombing punishment for a clear violator, let alone a unilateral United States Tomahawk missile-storm against a dictator who the White House (but not necessarily the rest of the world) believes ordered a chemical attack against its own citizens.

So the United States wants to appoint itself the selective enforcer of what Defense Secretary Chuck Hagel calls "the nearly century-old international norm against the use of chemical weapons," even though it has only been a signatory to that norm for 38 years, has carved out a legal exception for itself, and has a checkered history that includes preparing to deploy stockpiles of banned chemical weapons during World War II.

Worse yet, some war enthusiasts, including Democratic National Committee Chair Debbie Wasserman Schultz, are reaching back even before the 1925 treaty we signed in 1975, to The Hague Convention of 1899, which stated that signatories will abide by "the prohibition of the use of projectiles with the sole object to spread asphyxiating poisonous gases."

The only problem with citing this international norm as a casus belli for war against Syria? It only concerned war between states. There was no enforcement mechanism, let alone one that named the Pentagon as the enforcing army. Oh—and the United States never even signed the damned thing.

2) The 1993 Chemical Weapons Convention, or Convention on the Prohibition of the Development, Production, Stockpiling and Use of Chemical Weapons and on their Destruction. This is the relevant treaty signed by 189 states. Unhelpfully for the Syria interventionists, Syria isn't one of them.

The CWC prohibits "the Development, Production, Stockpiling and Use of Chemical Weapons," and mandates their destruction. All signatories were supposed to have destroyed their chemical stocks by April 2012, but as of December 2011 the eradication program had only hit 72 percent. One of the biggest scofflaws was also one of the two biggest possessors of chemical weapons: The United States of America, which as of the end of 2011 had destroyed 89.71 percent of its hoard.

So what's the CWC's enforcement regime? As even pro-war commentators will note (if they are honest), there isn't one. Richard Price, author of The Chemical Weapons Taboo, pointed out recently in Foreign Affairs that "Like the Geneva Protocol, the Chemical Weapons Convention does not explicitly stipulate its own enforcement mechanisms."

Instead of bombing campaigns from America or anyone else, violators of the treaty are subject to war crimes prosecutions at the International Criminal Court (ICC) in The Hague. And—mostly because of lobbying efforts from the United States—the ICC cannot go after dictators that do not recognize the court's legitimacy. Prosecutions of rogue actors must be referred to the ICC by the United Nations Security Council.

3) The 1998 Rome Statute of the International Criminal Court, which willed the ICC into being. The 122 countries that have ratified this treaty recognize the authority of the court to bring trials against people living within these countries who stand accused of genocide, war crimes, and crimes against humanity. The only time residents of non-signatory countries like Syria—or the United States—can be hauled in is at the request of the UN Security Council.

As the ICC's Wikipedia page succinctly notes, "During the negotiations that led to the Rome Statute, a large number of states argued that the Court should be allowed to exercise universal jurisdiction. However, this proposal was defeated due in large part to opposition from the United States." Assad might have been charged already had it not been for American diplomatic resistance to a more aggressive court.

Washington's relationship with the ICC can best be described as contentious and inconsistent, with Republicans especially under the Bush administration demanding all kinds of safeguards and exemptions against Americans ever being subject to international prosecution.

So where does that leave the Obama administration in terms of bombing Syria and international law? In such a bad place that even supporters are writing headlines like "Bomb Syria, Even if It Is Illegal," and "The U.S. Has No Legal Basis to Intervene in Syria." Why?

Because of another bit of international law that has gone largely unmentioned by the Obama administration: The United Nations Charter. This document states clearly that "All Members shall refrain in their international relations from the threat or use of force against the territorial integrity or political independence of any state, or in any other manner inconsistent with the Purposes of the United Nations."

This is what happens when a single country—or a single government, or single branch of government, or single executive sitting atop a single branch of government in a single country—declares itself the judge, jury, and executioner of "international norms." Those norms will be defined by the global sheriff, enforced selectively and inconsistently, with carveouts for the cop, and in such a way that will erode public support and democratic legitimacy over time.