When my younger son was nine years old, his dad and I watched helplessly as he changed from a happy-go-lucky child to one consumed with fear.

He worried that his food was contaminated and he stopped eating. He became convinced that sunlight would blind him and he stopped going outside to play. When he started washing his hands every few minutes, we finally recognized what was happening: our son had obsessive-compulsive disorder.

For the next few years my family wandered through the desert that all families with mental illness have to navigate – searching for appropriate medical practitioners, weighing the benefits and risks of pharmaceutical therapies, hoping for a cure – struggling to help our son as he traveled his own lonely path through friendships and school.

His elementary and middle school teachers were understanding. They saw firsthand how his OCD sabotaged his performance, were aware that he often finished tests early only to erase all his answers and start over, and over again, until he had worn holes in his paper. If he needed more time or a quiet place to work undistracted, they tried to give it to him.

High school was a different story. My son’s English teacher said that she was neither obligated nor willing to offer any accommodations because of his disability.

“It wouldn’t be fair,” she said, “to let him have more time to finish a test than the rest of the class.”

I’ve heard that argument against leveling the playing field plenty of times, and my response is always the same. We “level the playing field” when we let students wear glasses. A broken brain is just as much a physical disability as nearsighted eyes.

That’s why when my son was 14 years old, his dad and I began crossing another desert of sorts, navigating the legal landscape made easier because of the Americans With Disabilities Act. Passed in 1990, the ADA guarantees equal access to education and employment to people like my son. It gave us the force of law to compel his teachers to recognize his disability and adjust their instruction and assessment for him.

When it came time to take the SAT for college entrance, he was able to ask for a longer testing period. When he was accepted to college, he legally could have asked his professors for the same testing accommodations. He almost never did, fearful of incurring their annoyance and all too aware of the lingering stigma against the disabled.

This week the U.S. Senate had an opportunity to stand up for the disabled people of the world and it didn’t. Instead, senators fell five votes short of ratifying the U.N. Convention on the Rights of Persons with Disabilities. Nothing in the treaty is controversial or provocative. The disabled community advocated for it; 126 other countries have already ratified it.

Negotiated during George W. Bush’s term as president, the treaty was signed by President Barack Obama. Prominent Republicans such as former U.S. Sen. Bob Dole and Sen. John McCain argued for ratification. Rising Republican star Sen. Kelly Ayotte from New Hampshire voted for the treaty because it “takes a step toward making it easier for disabled Americans to live and work overseas, without impinging on U.S. sovereignty or Congress’ authority to determine our disability laws.”

But 38 Republicans voted no.

Rick Santorum argued that the treaty could change U.S. law or be used as a standard in court cases, though only U.S. law can be the basis for litigations in American courtrooms.

Mike Farris, head of the Home School Legal Defense group, told U.S. News and World Report that the treaty shouldn’t be ratified because establishing legal rights for the disabled would conflict with “the traditional right of parents to direct the education and upbringing of their child with special needs.”

That, too, seems a specious argument. The Americans With Disabilities Act, which is the model for the treaty, has given me more, not less, ability to direct my special needs child’s education and to be a better, more effective advocate for him.

Rather, the real reason Republicans voted no was because of their ideological antipathy to the United Nations. Blocking the ratification was done not with thoughtful consideration for the goals of the treaty – “To promote, protect and ensure the full and equal enjoyment of all human rights and fundamental freedoms by all persons with disabilities, and to promote respect for their inherent dignity”– but in a knee-jerk rejection of anything related to the U.N.

That ideology is also why the United States is the only country besides Somalia that hasn’t ratified the U.N. Convention on the Rights of the Child. Like the convention on the disabled, it is a life-affirming list of human rights. Blocking ratification of either one is a shameful display of political theater.