Which level of government do you think should have the responsibility for protecting the rights of the disabled — local, state, federal or the United Nations? The United States has been a global leader in protecting the disabled and advancing its interests. Over the past few decades, this has been accomplished through a combination of federal, state and local laws and regulations. But now the United Nations is trying to get involved.

The United Nations was originally established to prevent war among countries. Having repetitively failed in that mission, it has been interjecting itself into virtually every other aspect of human life, including demands for various forms of global taxes to be collected and distributed by U.N. bureaucrats. On May 18, President Obama sent the U.N. Convention on the Rights of Persons With Disabilities to the Senate for ratification. Such a treaty requires a two-thirds vote of the Senate. The Senate Foreign Relations Committee has just passed this convention, and it is now awaiting floor action by the entire Senate.

You may be thinking, “Yes, we should protect the rights of people with disabilities. So, even though the U.N. is ineffective, what could be the harm in voting for it?” This appears to have been the view of the majority of the members of the Senate Foreign Relations Committee. It also appears that few of them have actually read the convention. One who did is freshman Sen. Mike Lee, a constitutional scholar and rising star, who, along with Sens. Jim DeMint, James M. Inhofe, James E. Risch and Marco Rubio, all Republicans, has been raising warning signals. As with so many other U.N. conventions, the language is vague and in many ways infinitely elastic and thus may be used to overturn many U.S. constitutional protections.

Article 4(1)(e) demands that “every person, organization, or private enterprise” must eliminate discrimination on the basis of disability. Taken literally, which some lawyers are sure to do, every homeowner might be required to install wheelchair ramps or even elevators in their homes, regardless of the cost. This also means that the legal standard for the number of handicapped spaces required for parking at your local stores or houses of worship would be established by the U.N. Such issues should be decided at the local or state level, not by a committee of unelected international bureaucrats.

Mr. Lee and his colleagues have written: “The very purpose of a treaty is to advance a specific U.S. security or economic interest, and the United States should only join those treaties that make us a stronger or safer nation. [T]he issues concerned in this Convention would be better addressed in a format that would not require the ratification of a legally binding international treaty that would carry the same authority as the Constitution.” Our Founding Fathers, notably both Washington and Jefferson, warned about the dangers of foreign entanglements that would undermine our sovereignty and threaten our domestic affairs.

The U.S. Constitution protects the rights of free speech, press, assembly, the right to bear arms, etc. These rights do not impose a cost on fellow citizens. So-called “positive” or “active” rights, such as the right to housing and medical care, impose costs on one’s fellow citizens. For example, if the government grants you the right to free medical care, it is implicitly saying that some other citizen has the responsibility and must be coerced through the force of law to cover the cost of your medical care. That is why the protection of the disabled should largely be done at the local level, through such things as building codes, or at the state level, through the provision of educational opportunities, where it is both constitutional and most likely to meet real needs at reasonable cost.

The proposed U.N. convention would trump national, state and local laws. Under Article 4(1)(a), the convention requires that American law conform to the standards of the U.N. Article 4(2) implicitly obligates the U.S., as a wealthy nation, to fund disability programs in nations that could not afford their own programs.

The definition of a “disability,” as noted, is infinitely elastic. I have a minor disability — a lack of sight in one eye. If this treaty is ratified, I am willing to bet that some time in the future an enterprising lawyer will find some way of making others pay for those with my “disability” at nice profit. There is no obvious way to stop this mission creep given that most people have some minor physical or mental defects that the U.N. bureaucrats and lawyers will exploit to the last person and the last dollar.

As Mr. Lee and the other senators noted: “Should the United States accede to this treaty, we will be obligated to write a status report every four years regarding our disability laws and receive criticism and recommendations from a committee of representatives from countries that have lower standards for the disabled than our own. We do not know the scope of this report or its financial and labor costs to the American taxpayer.” In sum, the proposed convention would undermine U.S. sovereignty and laws, leave the disabled with less cost-effective and even counterproductive protections, and saddle the taxpayer with a potential limitless liability. It’s not a good idea.