Congress passed the No Child Left Behind Act overwhelmingly in December 2001. NCLB’s popularity was partly political and partly geopolitical. Republicans wanted a legislative victory for the new president, and legislators sought to demonstrate U.S. solidarity in the wake of 9/11. But adding to its appeal was the mom-and-apple-pie promise that it would raise overall achievement in math and reading while narrowing the test score gaps dividing rich from poor, and black and Hispanic from white. Recent results from two different sets of international tests suggest that NCLB has failed to deliver on that promise.

The Program for International Student Assessment was first administered to 15-year-olds in 2000, testing them on mathematics, reading, and science. Students in the United States earned an overall math score of 493 on the 1000 point scale, seven points below average, placing us 18th out of the 27 participating countries. Three years later, PISA results showed no significant change in U.S. math performance. But according to the latest report the U.S. suffered a significant decline in mathematics achievement between 2003 and 2006. We now score 474 — in 25th place among the 30 participating countries.

U.S. reading scores fell somewhat on PISA between 2000 and 2003, but not enough for the difference to be considered significant by OECD statisticians. Regrettably, no reading results are available for 2006, due to a printing error.

PISA also tests students in science, a subject area not specifically targeted by NCLB. Still, it seems reasonable to expect that if the law were actually improving math and reading performance, students might have an easier time with science as a result. As it happens, our overall science score dropped from 499 in 2000, to 489 last year, and our ranking fell from 14th out of 27 countries to 21st out of 30 countries.

But this decline actually understates the drop in our science performance, because several other nations have been getting worse as well, bringing down the overall average. When we look only at students’ answers to the questions that were asked in both 2003 and 2006, the U.S. suffered a 13.5 point drop — the fourth largest decline among the 30 participating countries.

So, according to the PISA test, U.S. students have suffered overall stagnation or decline in math, reading, and science in the years since NCLB was passed. What about the score gaps? Figures for racial and ethnic achievement for both 2000 and 2006 are only available on the science test, and they show a 13 point narrowing of the Hispanic/​white gap and a 14 point increase in the black/​white gap. Since these changes are roughly equal in size but opposite in direction, it is hard to imagine that either was caused by NCLB, which has no obvious features that might lead such a disparate effect on Hispanic and black students.

Taken together, the PISA test data suggest NCLB has been a failure. That same picture is painted by a separate test of 4th grade students: the Program on International Reading Literacy Survey. According to PIRLS, U.S. 4th grade reading achievement fell, though only by a negligible 2 points, between 2001 and 2006.

While NCLB hasn’t improved achievement or closed the gaps, it has succeeded in making public schools far more expensive to operate. The average estimate of the costs imposed by NCLB’s accountability provisions hovers around 5% of combined state and local spending. Conservatively speaking, that amounts to roughly $16 billion in additional spending, annually. And since those accountability provisions appear to have done no good, we seem to have wasted almost $100 billion since NCLB was enacted.

But this isn’t just another story about federal waste or “unfunded mandates.” It’s a story about the millions of American children whose chances of receiving a good education have been gambled away because Congress backed the wrong policy horse. Our elected representatives went to the track one day and bet our money on a long-shot — on the idea that increased federal intrusion in the classroom would promote academic excellence. They, and we, lost. But of course the biggest losers are American kids — particularly the lowest-performing students, whom the law was especially intended to help.

Now that the results are in, only obstinacy and foolishness would lead us to continue throwing money at NCLB. It is time for Congress to return authority over education to the states and the people, where the Constitution so presciently left it.