WASHINGTON — By the end of the school year, every teacher of every major subject in every school will be highly qualified. That's the government's promise, anyway.

The reality will be far less rosy, say experts who have analyzed how states are responding to President Bush's education law and its unprecedented review of teacher quality.

As the centerpiece of his domestic agenda, the No Child Left Behind Act aims to dramatically improve learning by ensuring that all students have highly qualified teachers.

Yet in a nation of 3 million teachers, the definition of highly qualified varies widely and may not ensure quality at all — not what Bush and Congress intended.

Given considerable leeway, many states are declaring their teachers to be highly qualified without making sure those teachers know their subjects, independent reviews show.

The law also lacks specific penalties for states that fail to get all their teachers qualified, which could hamper enforcement by the Education Department.

Already, most states say that more than 90 percent of their teachers are highly qualified.

In Utah, just under 70 percent of Utah teachers were considered highly qualified during the 2003-04 school year, the last count taken, said Joan Patterson, educator licensing coordinator at the State Office of Education. But that number probably is higher.

The number counts only teachers who are highly qualified by nature of their college degrees. The state until this week has been unable to track other ways teachers become highly qualified, Patterson said. New technology is ready to go, and a new count is coming up.

On a national scale, the notion that top teachers fill most classrooms is greeted skeptically because of questions over how the states define quality and how they collect their data.

"It's an unkept promise," said Chester Finn Jr., a former assistant education secretary who runs the Fordham Foundation think tank in Washington. "Worse yet, it's the illusion of a kept promise."

Under the law, states have until the end of the 2005-06 school year to make sure teachers in every core class, from math and science to arts and languages, have a bachelor's degree, a state license or certificate, and are competent in every subject they teach. Teachers in isolated, rural areas have an extra year to qualify.

The requirement that teachers are competent in their subjects is the driving force, as the government tries for the first time to ensure teachers know their subjects.

Teachers can prove they know their content by passing a test or having a major in each subject they handle. But many teachers find those options unrealistic or demeaning.