You are correct in the fact that the treaty itself will have no power and that it’s up to the signatory countries to individually enact laws to enforce its application. The problem lies in enforcement. The supremacy clause of the constitution gives international treaties ratified by the senate the same amount of power as constitutional law. If the treaty is signed and not opposed by at least 34 senators then US lawmakers will have no choice to enact laws based on the recommendations of the treaties advisory panel. We are a nation that respects the treaties we sign. The danger comes from other nations that will sign the treaty but have a historical record of ignoring UN regulations. I understand that this is both an emotionally and partisan charged issue but if you are able to remove yourself from those limitations and view this treaty from a facts based perspective its clearly a bad policy move for the US. The fact that we respect the rule of law clearly works against us in a global perspective. With the signing of this treaty we effectively give a veto to Iran and its benefactors on who we are able to makes arms deals with. The fact that America will have a seat on this panel means little as many of the nations we have typically concerned ourselves with regarding illicit arms trade have little respect for the rule of UN law. Iran, China, North Korea, Bhutan, The Malaysian territories and Syria all have signaled support of this treaty but all have a history of ignoring treaties and accords that they have signed. This is almost never a matter of policy as it is a matter of an inability to enforce at a national level. So whether or not you are afraid of or excited for the prospect of Gun control in America ask yourself first if it is good International policy.