Mexican President Felipe Calderón is in Washington for a two day state visit from May 19-20. He and President Obama have a lot to talk about, ranging from reaffirming a shared commitment to the North American Free Trade Agreement to the vital need for both countries to emphasize competitiveness, technological innovation, and creative entrepreneurship. In Mexico, these policies will increase growth and employment and reduce the economic pressures that drive illegal immigration across the U.S. border.

But front and center in the visit will be President Calderón’s battle with the deadly Mexican drug cartels. This battle has so far claimed over 22,000 Mexican lives since 2006. Under President Bush, the U.S. launched the Merida Initiative, which has delivered aircraft, police training, computers, and drug detection machinery to Mexico’s federal police. Because Mexico’s problems affect the U.S., the Initiative was a wise response, and both Presidents should seek to build upon it.

Unfortunately, one of the policies the presidents support is not wise. When President Obama visited Mexico in 2009, he called on the Senate to ratify the Inter-American Convention Against the Illicit Manufacture of and Trafficking in Firearms, known by its Spanish acronym CIFTA. The convention promises to stem the flow of firearms legally purchased in the U.S. and illegally exported to Mexico. Today, when he addresses Congress, President Calderón is likely to urge the Senate to ratify CIFTA, which was negotiated under the auspices of the Organization of American States, as a gesture to show that his battle has American backing.

President Calderón deserves American support. But not at the cost of American liberties. CIFTA is a poorly-drafted treaty that would have wide-ranging effects in the United States. At heart, it would require the U.S. to set up a licensing system for the manufacture of any part of a firearm. And that means any part: a screw or a spring, for example. The Mexican crisis is no reason to turn the manufacture of common, simple items like these into a federal case, but that is exactly what the treaty does.

But it gets worse than that. The treaty doesn’t simply criminalize manufacturing. It also criminalizes assembly of any part of a firearm. By the same token, simply attaching a sling to a legally-owned hunting rifle would qualify as assembling a firearm, and would require a government license. So would tightening a screw, or attaching a sight. None of this has the slightest connection to the smuggling of guns into Mexico. All the treaty would do is vastly expand the power of the administrative state, and criminalize the recreational pursuits of millions of innocent Americans.

But it gets even worse than that. The treaty also prohibits the “counseling” of any of the activities it regulates. In other words, it criminalizes speech. Under the treaty, even saying that someone should attach a sling to a rifle without a license would be a crime. Thank goodness we in the United States have the First Amendment to protect us from foolishness like this. But not everyone is so lucky. The treaty is custom made for dictators like Venezuela’s Hugo Chavez, because it allows them to claim they are upholding the treaty every time they arrest an opponent.

And speaking of Chavez, because Venezuela is a signatory, U.S. ratification would entitle his regime to legal assistance from the U.S. every time it tried to extradite a Venezuelan dissident for supposedly violating the treaty. Furthermore, the treaty requires the U.S. to collect information on all its licensed manufactures and assemblers, and to hand it over to all the other signatories, including Chavez. All of this has nothing to do with arms smuggling, but it would have an enormous effect on the privacy of Americans, and on the ability of the U.S. to serve as a haven for exiles.

Even if the treaty worked, it wouldn’t be worth it. But it won’t work. Indeed, it hasn’t worked. The treaty hasn’t stopped Venezuela from smuggling sophisticated weapons to the FARC guerillas in Colombia, and seeking to overthrow the democratically elected government of President Alvaro Uribe. The OAS doesn’t even regard FARC as a terrorist organization. At best, the liberal left’s enthusiasm for CIFTA is a sign of their detachment from reality, of their belief that signing a treaty is the same thing as solving a problem. At worst, it’s a cover for advancing a domestic agenda that has nothing to do with U.S.-Mexican relations.

Every time a gun crosses the U.S.-Mexican border without a proper export license, existing U.S. law is being violated. And the same thing is true every time an individual crosses the border without proper paperwork. Arms smuggling is a symptom of a much larger problem: the border is not properly controlled. That is the problem that the U.S. and Mexico need to focus on.

Vastly expanding the power of the federal state and criminalizing speech will only endanger American liberties and bring treaties, and the law, into contempt. This is the kind of gesture that America should avoid making, because it will do nothing for Mexico and harm America in the bargain.

Ted Bromund, Ph.D., is the Margaret Thatcher Senior Research Fellow at The Heritage Foundation. Ray Walser is a Senior Policy Analyst specializing in Latin America at Heritage.