Students in Illinois have won the right to begin their school day with a "moment of silence," after the U.S. Supreme Court declined to review the case at the request of opponents who argued such behavior promoted prayer in school.

The debate began in 2007 when Illinois state legislators adjusted the wording of a law that made "a brief period of silence" for silent prayer or silent reflection mandatory in schools.

Soon after, Buffalo Grove High School student Dawn Sherman, daughter of well-known Illinois atheist activist Rob Sherman, sued, claiming the moment of silence took time away from her learning.

Two years later, a district judge ruled that the Illinois law was unconstitutional because it was endorsing prayer and religion in school. He placed an injunction against it, and schools immediately stopped allowing the moment of silence.

By last October, the case had been reviewed by the U.S. Seventh Circuit Court of Appeals, which voted 2-1 to overturn the district judge's ruling.

"Nothing in the text ... limits students' thoughts during the period of silence; the text mandates only one thing — silence," wrote Judge Daniel Manion in the ruling.

The practice was reinstituted in Illinois schools several months after the circuit court ruling, and students again were given eight, 10 or 15 seconds of silence.

Illinois isn't the first state to offer students a quiet moment during school mornings.

In Georgia, the l994 law states, "teachers must conduct a period of reflection for not more than one minute each school day."

Virginia school boards are required to "establish daily moments of silence for meditation, prayer or other silent activity in every classroom in the public schools of Virginia. No other activities may be allowed during this time," according to the National Conference of State Legislatures.

New Hampshire allows up to five minutes for such reflection, while most other states stick to the one-minute-or-less time frame.

Utah's code, adopted in 1996, states, "a teacher may provide for the observation of a period of silence each day."

Alabama had a law that authorized teachers to lead a minute of prayer and even call on students to offer prayers in class, but a lawsuit and a subsequent Supreme Court decision found its law unconstitutional.

Alabama's code now focuses on the benefits of simple, quiet reflection.

"At the opening of school every day in each public school classroom, the teacher in charge shall conduct a brief period of quiet reflection for 60 seconds with the participation of every pupil in the classroom," according to the state's code. "The moment of quiet reflection ... is not intended to be and shall not be conducted as a religious service or exercise, but shall be considered an opportunity for a moment of silent reflection on the anticipated activities of the day or event."

Texas' law was also challenged by a couple who argued that the state-mandated "observance of one minute of silence at each school in the district following the recitation of the pledges of allegiance to the United States and Texas flags" was unconstitutional.

But U.S. District Judge Barbara Lynn upheld the law according to the Times Record News, of Wichita, Texas, writing that the "primary effect of the statute is to institute a moment of silence, not to advance or inhibit religion."

The concern over religion in the classroom has existed for decades, with two major Supreme Court decisions issued in the 1960s.

In 1962 the Supreme Court ruled in Engel v. Vitale that it was unconstitutional for officials to compose a prayer and require students to recite it.

A year later, the high court declared that school-sponsored Bible readings were unconstitutional.